9.1.2. The cx2341x driver¶
9.1.2.1. Memory at cx2341x chips¶
This section describes the cx2341x memory map and documents some of the register space.
Note
the memory long words are little-endian (‘intel format’).
Warning
This information was figured out from searching through the memory and registers, this information may not be correct and is certainly not complete, and was not derived from anything more than searching through the memory space with commands like:
ivtvctl -O min=0x02000000,max=0x020000ff
So take this as is, I’m always searching for more stuff, it’s a large register space :-).
9.1.2.1.1. Memory Map¶
The cx2341x exposes its entire 64M memory space to the PCI host via the PCI BAR0 (Base Address Register 0). The addresses here are offsets relative to the address held in BAR0.
0x00000000-0x00ffffff Encoder memory space
0x00000000-0x0003ffff Encode.rom
???-??? MPEG buffer(s)
???-??? Raw video capture buffer(s)
???-??? Raw audio capture buffer(s)
???-??? Display buffers (6 or 9)
0x01000000-0x01ffffff Decoder memory space
0x01000000-0x0103ffff Decode.rom
???-??? MPEG buffers(s)
0x0114b000-0x0115afff Audio.rom (deprecated?)
0x02000000-0x0200ffff Register Space
9.1.2.1.2. Registers¶
The registers occupy the 64k space starting at the 0x02000000 offset from BAR0. All of these registers are 32 bits wide.
DMA Registers 0x000-0xff:
0x00 - Control:
0=reset/cancel, 1=read, 2=write, 4=stop
0x04 - DMA status:
1=read busy, 2=write busy, 4=read error, 8=write error, 16=link list error
0x08 - pci DMA pointer for read link list
0x0c - pci DMA pointer for write link list
0x10 - read/write DMA enable:
1=read enable, 2=write enable
0x14 - always 0xffffffff, if set any lower instability occurs, 0x00 crashes
0x18 - ??
0x1c - always 0x20 or 32, smaller values slow down DMA transactions
0x20 - always value of 0x780a010a
0x24-0x3c - usually just random values???
0x40 - Interrupt status
0x44 - Write a bit here and shows up in Interrupt status 0x40
0x48 - Interrupt Mask
0x4C - always value of 0xfffdffff,
if changed to 0xffffffff DMA write interrupts break.
0x50 - always 0xffffffff
0x54 - always 0xffffffff (0x4c, 0x50, 0x54 seem like interrupt masks, are
3 processors on chip, Java ones, VPU, SPU, APU, maybe these are the
interrupt masks???).
0x60-0x7C - random values
0x80 - first write linked list reg, for Encoder Memory addr
0x84 - first write linked list reg, for pci memory addr
0x88 - first write linked list reg, for length of buffer in memory addr
(|0x80000000 or this for last link)
0x8c-0xdc - rest of write linked list reg, 8 sets of 3 total, DMA goes here
from linked list addr in reg 0x0c, firmware must push through or
something.
0xe0 - first (and only) read linked list reg, for pci memory addr
0xe4 - first (and only) read linked list reg, for Decoder memory addr
0xe8 - first (and only) read linked list reg, for length of buffer
0xec-0xff - Nothing seems to be in these registers, 0xec-f4 are 0x00000000.
Memory locations for Encoder Buffers 0x700-0x7ff:
These registers show offsets of memory locations pertaining to each buffer area used for encoding, have to shift them by <<1 first.
0x07F8: Encoder SDRAM refresh
0x07FC: Encoder SDRAM pre-charge
Memory locations for Decoder Buffers 0x800-0x8ff:
These registers show offsets of memory locations pertaining to each buffer area used for decoding, have to shift them by <<1 first.
0x08F8: Decoder SDRAM refresh
0x08FC: Decoder SDRAM pre-charge
Other memory locations:
0x2800: Video Display Module control
0x2D00: AO (audio output?) control
0x2D24: Bytes Flushed
0x7000: LSB I2C write clock bit (inverted)
0x7004: LSB I2C write data bit (inverted)
0x7008: LSB I2C read clock bit
0x700c: LSB I2C read data bit
0x9008: GPIO get input state
0x900c: GPIO set output state
0x9020: GPIO direction (Bit7 (GPIO 0..7) - 0:input, 1:output)
0x9050: SPU control
0x9054: Reset HW blocks
0x9058: VPU control
0xA018: Bit6: interrupt pending?
0xA064: APU command
9.1.2.1.3. Interrupt Status Register¶
The definition of the bits in the interrupt status register 0x0040, and the interrupt mask 0x0048. If a bit is cleared in the mask, then we want our ISR to execute.
bit 31 Encoder Start Capture
bit 30 Encoder EOS
bit 29 Encoder VBI capture
bit 28 Encoder Video Input Module reset event
bit 27 Encoder DMA complete
bit 24 Decoder audio mode change detection event (through event notification)
bit 22 Decoder data request
bit 20 Decoder DMA complete
bit 19 Decoder VBI re-insertion
bit 18 Decoder DMA err (linked-list bad)
9.1.2.2. Missing documentation¶
Encoder API post(?)
Decoder API post(?)
Decoder VTRACE event
9.1.2.3. The cx2341x firmware upload¶
This document describes how to upload the cx2341x firmware to the card.
9.1.2.3.1. How to find¶
See the web pages of the various projects that uses this chip for information on how to obtain the firmware.
The firmware stored in a Windows driver can be detected as follows:
Each firmware image is 256k bytes.
The 1st 32-bit word of the Encoder image is 0x0000da7
The 1st 32-bit word of the Decoder image is 0x00003a7
The 2nd 32-bit word of both images is 0xaa55bb66
9.1.2.3.2. How to load¶
Issue the FWapi command to stop the encoder if it is running. Wait for the command to complete.
Issue the FWapi command to stop the decoder if it is running. Wait for the command to complete.
Issue the I2C command to the digitizer to stop emitting VSYNC events.
Issue the FWapi command to halt the encoder’s firmware.
Sleep for 10ms.
Issue the FWapi command to halt the decoder’s firmware.
Sleep for 10ms.
Write 0x00000000 to register 0x2800 to stop the Video Display Module.
Write 0x00000005 to register 0x2D00 to stop the AO (audio output?).
Write 0x00000000 to register 0xA064 to ping? the APU.
Write 0xFFFFFFFE to register 0x9058 to stop the VPU.
Write 0xFFFFFFFF to register 0x9054 to reset the HW blocks.
Write 0x00000001 to register 0x9050 to stop the SPU.
Sleep for 10ms.
Write 0x0000001A to register 0x07FC to init the Encoder SDRAM’s pre-charge.
Write 0x80000640 to register 0x07F8 to init the Encoder SDRAM’s refresh to 1us.
Write 0x0000001A to register 0x08FC to init the Decoder SDRAM’s pre-charge.
Write 0x80000640 to register 0x08F8 to init the Decoder SDRAM’s refresh to 1us.
Sleep for 512ms. (600ms is recommended)
Transfer the encoder’s firmware image to offset 0 in Encoder memory space.
Transfer the decoder’s firmware image to offset 0 in Decoder memory space.
Use a read-modify-write operation to Clear bit 0 of register 0x9050 to re-enable the SPU.
Sleep for 1 second.
Use a read-modify-write operation to Clear bits 3 and 0 of register 0x9058 to re-enable the VPU.
Sleep for 1 second.
Issue status API commands to both firmware images to verify.
9.1.2.4. How to call the firmware API¶
The preferred calling convention is known as the firmware mailbox. The mailboxes are basically a fixed length array that serves as the call-stack.
Firmware mailboxes can be located by searching the encoder and decoder memory for a 16 byte signature. That signature will be located on a 256-byte boundary.
Signature:
0x78, 0x56, 0x34, 0x12, 0x12, 0x78, 0x56, 0x34,
0x34, 0x12, 0x78, 0x56, 0x56, 0x34, 0x12, 0x78
The firmware implements 20 mailboxes of 20 32-bit words. The first 10 are reserved for API calls. The second 10 are used by the firmware for event notification.
Index
Name
0
Flags
1
Command
2
Return value
3
Timeout
4-19
Parameter/Result
The flags are defined in the following table. The direction is from the perspective of the firmware.
Bit
Direction
Purpose
2
O
Firmware has processed the command.
1
I
Driver has finished setting the parameters.
0
I
Driver is using this mailbox.
The command is a 32-bit enumerator. The API specifics may be found in this chapter.
The return value is a 32-bit enumerator. Only two values are currently defined:
0=success
-1=command undefined.
There are 16 parameters/results 32-bit fields. The driver populates these fields with values for all the parameters required by the call. The driver overwrites these fields with result values returned by the call.
The timeout value protects the card from a hung driver thread. If the driver doesn’t handle the completed call within the timeout specified, the firmware will reset that mailbox.
To make an API call, the driver iterates over each mailbox looking for the first one available (bit 0 has been cleared). The driver sets that bit, fills in the command enumerator, the timeout value and any required parameters. The driver then sets the parameter ready bit (bit 1). The firmware scans the mailboxes for pending commands, processes them, sets the result code, populates the result value array with that call’s return values and sets the call complete bit (bit 2). Once bit 2 is set, the driver should retrieve the results and clear all the flags. If the driver does not perform this task within the time set in the timeout register, the firmware will reset that mailbox.
Event notifications are sent from the firmware to the host. The host tells the firmware which events it is interested in via an API call. That call tells the firmware which notification mailbox to use. The firmware signals the host via an interrupt. Only the 16 Results fields are used, the Flags, Command, Return value and Timeout words are not used.
9.1.2.5. OSD firmware API description¶
Note
this API is part of the decoder firmware, so it’s cx23415 only.
9.1.2.5.1. CX2341X_OSD_GET_FRAMEBUFFER¶
Enum: 65/0x41
9.1.2.5.1.1. Description¶
Return base and length of contiguous OSD memory.
9.1.2.5.1.2. Result[0]¶
OSD base address
9.1.2.5.1.3. Result[1]¶
OSD length
9.1.2.5.2. CX2341X_OSD_GET_PIXEL_FORMAT¶
Enum: 66/0x42
9.1.2.5.2.1. Description¶
Query OSD format
9.1.2.5.2.2. Result[0]¶
0=8bit index 1=16bit RGB 5:6:5 2=16bit ARGB 1:5:5:5 3=16bit ARGB 1:4:4:4 4=32bit ARGB 8:8:8:8
9.1.2.5.3. CX2341X_OSD_SET_PIXEL_FORMAT¶
Enum: 67/0x43
9.1.2.5.3.1. Description¶
Assign pixel format
9.1.2.5.3.2. Param[0]¶
0=8bit index
1=16bit RGB 5:6:5
2=16bit ARGB 1:5:5:5
3=16bit ARGB 1:4:4:4
4=32bit ARGB 8:8:8:8
9.1.2.5.4. CX2341X_OSD_GET_STATE¶
Enum: 68/0x44
9.1.2.5.4.1. Description¶
Query OSD state
9.1.2.5.4.2. Result[0]¶
Bit 0 0=off, 1=on
Bits 1:2 alpha control
Bits 3:5 pixel format
9.1.2.5.5. CX2341X_OSD_SET_STATE¶
Enum: 69/0x45
9.1.2.5.5.1. Description¶
OSD switch
9.1.2.5.5.2. Param[0]¶
0=off, 1=on
9.1.2.5.6. CX2341X_OSD_GET_OSD_COORDS¶
Enum: 70/0x46
9.1.2.5.6.1. Description¶
Retrieve coordinates of OSD area blended with video
9.1.2.5.6.2. Result[0]¶
OSD buffer address
9.1.2.5.6.3. Result[1]¶
Stride in pixels
9.1.2.5.6.4. Result[2]¶
Lines in OSD buffer
9.1.2.5.6.5. Result[3]¶
Horizontal offset in buffer
9.1.2.5.6.6. Result[4]¶
Vertical offset in buffer
9.1.2.5.7. CX2341X_OSD_SET_OSD_COORDS¶
Enum: 71/0x47
9.1.2.5.7.1. Description¶
Assign the coordinates of the OSD area to blend with video
9.1.2.5.7.2. Param[0]¶
buffer address
9.1.2.5.7.3. Param[1]¶
buffer stride in pixels
9.1.2.5.7.4. Param[2]¶
lines in buffer
9.1.2.5.7.5. Param[3]¶
horizontal offset
9.1.2.5.7.6. Param[4]¶
vertical offset
9.1.2.5.8. CX2341X_OSD_GET_SCREEN_COORDS¶
Enum: 72/0x48
9.1.2.5.8.1. Description¶
Retrieve OSD screen area coordinates
9.1.2.5.8.2. Result[0]¶
top left horizontal offset
9.1.2.5.8.3. Result[1]¶
top left vertical offset
9.1.2.5.8.4. Result[2]¶
bottom right horizontal offset
9.1.2.5.8.5. Result[3]¶
bottom right vertical offset
9.1.2.5.9. CX2341X_OSD_SET_SCREEN_COORDS¶
Enum: 73/0x49
9.1.2.5.9.1. Description¶
Assign the coordinates of the screen area to blend with video
9.1.2.5.9.2. Param[0]¶
top left horizontal offset
9.1.2.5.9.3. Param[1]¶
top left vertical offset
9.1.2.5.9.4. Param[2]¶
bottom left horizontal offset
9.1.2.5.9.5. Param[3]¶
bottom left vertical offset
9.1.2.5.10. CX2341X_OSD_GET_GLOBAL_ALPHA¶
Enum: 74/0x4A
9.1.2.5.10.1. Description¶
Retrieve OSD global alpha
9.1.2.5.10.2. Result[0]¶
global alpha: 0=off, 1=on
9.1.2.5.10.3. Result[1]¶
bits 0:7 global alpha
9.1.2.5.11. CX2341X_OSD_SET_GLOBAL_ALPHA¶
Enum: 75/0x4B
9.1.2.5.11.1. Description¶
Update global alpha
9.1.2.5.11.2. Param[0]¶
global alpha: 0=off, 1=on
9.1.2.5.11.3. Param[1]¶
global alpha (8 bits)
9.1.2.5.11.4. Param[2]¶
local alpha: 0=on, 1=off
9.1.2.5.12. CX2341X_OSD_SET_BLEND_COORDS¶
Enum: 78/0x4C
9.1.2.5.12.1. Description¶
Move start of blending area within display buffer
9.1.2.5.12.2. Param[0]¶
horizontal offset in buffer
9.1.2.5.12.3. Param[1]¶
vertical offset in buffer
9.1.2.5.13. CX2341X_OSD_GET_FLICKER_STATE¶
Enum: 79/0x4F
9.1.2.5.13.1. Description¶
Retrieve flicker reduction module state
9.1.2.5.13.2. Result[0]¶
flicker state: 0=off, 1=on
9.1.2.5.14. CX2341X_OSD_SET_FLICKER_STATE¶
Enum: 80/0x50
9.1.2.5.14.1. Description¶
Set flicker reduction module state
9.1.2.5.14.2. Param[0]¶
State: 0=off, 1=on
9.1.2.5.15. CX2341X_OSD_BLT_COPY¶
Enum: 82/0x52
9.1.2.5.15.1. Description¶
BLT copy
9.1.2.5.15.2. Param[0]¶
'0000' zero
'0001' ~destination AND ~source
'0010' ~destination AND source
'0011' ~destination
'0100' destination AND ~source
'0101' ~source
'0110' destination XOR source
'0111' ~destination OR ~source
'1000' ~destination AND ~source
'1001' destination XNOR source
'1010' source
'1011' ~destination OR source
'1100' destination
'1101' destination OR ~source
'1110' destination OR source
'1111' one
9.1.2.5.15.3. Param[1]¶
Resulting alpha blending
‘01’ source_alpha
‘10’ destination_alpha
‘11’ source_alpha*destination_alpha+1 (zero if both source and destination alpha are zero)
9.1.2.5.15.4. Param[2]¶
'00' output_pixel = source_pixel
'01' if source_alpha=0:
output_pixel = destination_pixel
if 256 > source_alpha > 1:
output_pixel = ((source_alpha + 1)*source_pixel +
(255 - source_alpha)*destination_pixel)/256
'10' if destination_alpha=0:
output_pixel = source_pixel
if 255 > destination_alpha > 0:
output_pixel = ((255 - destination_alpha)*source_pixel +
(destination_alpha + 1)*destination_pixel)/256
'11' if source_alpha=0:
source_temp = 0
if source_alpha=255:
source_temp = source_pixel*256
if 255 > source_alpha > 0:
source_temp = source_pixel*(source_alpha + 1)
if destination_alpha=0:
destination_temp = 0
if destination_alpha=255:
destination_temp = destination_pixel*256
if 255 > destination_alpha > 0:
destination_temp = destination_pixel*(destination_alpha + 1)
output_pixel = (source_temp + destination_temp)/256
9.1.2.5.15.5. Param[3]¶
width
9.1.2.5.15.6. Param[4]¶
height
9.1.2.5.15.7. Param[5]¶
destination pixel mask
9.1.2.5.15.8. Param[6]¶
destination rectangle start address
9.1.2.5.15.9. Param[7]¶
destination stride in dwords
9.1.2.5.15.10. Param[8]¶
source stride in dwords
9.1.2.5.15.11. Param[9]¶
source rectangle start address
9.1.2.5.16. CX2341X_OSD_BLT_FILL¶
Enum: 83/0x53
9.1.2.5.16.1. Description¶
BLT fill color
9.1.2.5.16.2. Param[0]¶
Same as Param[0] on API 0x52
9.1.2.5.16.3. Param[1]¶
Same as Param[1] on API 0x52
9.1.2.5.16.4. Param[2]¶
Same as Param[2] on API 0x52
9.1.2.5.16.5. Param[3]¶
width
9.1.2.5.16.6. Param[4]¶
height
9.1.2.5.16.7. Param[5]¶
destination pixel mask
9.1.2.5.16.8. Param[6]¶
destination rectangle start address
9.1.2.5.16.9. Param[7]¶
destination stride in dwords
9.1.2.5.16.10. Param[8]¶
color fill value
9.1.2.5.17. CX2341X_OSD_BLT_TEXT¶
Enum: 84/0x54
9.1.2.5.17.1. Description¶
BLT for 8 bit alpha text source
9.1.2.5.17.2. Param[0]¶
Same as Param[0] on API 0x52
9.1.2.5.17.3. Param[1]¶
Same as Param[1] on API 0x52
9.1.2.5.17.4. Param[2]¶
Same as Param[2] on API 0x52
9.1.2.5.17.5. Param[3]¶
width
9.1.2.5.17.6. Param[4]¶
height
9.1.2.5.17.7. Param[5]¶
destination pixel mask
9.1.2.5.17.8. Param[6]¶
destination rectangle start address
9.1.2.5.17.9. Param[7]¶
destination stride in dwords
9.1.2.5.17.10. Param[8]¶
source stride in dwords
9.1.2.5.17.11. Param[9]¶
source rectangle start address
9.1.2.5.17.12. Param[10]¶
color fill value
9.1.2.5.18. CX2341X_OSD_SET_FRAMEBUFFER_WINDOW¶
Enum: 86/0x56
9.1.2.5.18.1. Description¶
Positions the main output window on the screen. The coordinates must be such that the entire window fits on the screen.
9.1.2.5.18.2. Param[0]¶
window width
9.1.2.5.18.3. Param[1]¶
window height
9.1.2.5.18.4. Param[2]¶
top left window corner horizontal offset
9.1.2.5.18.5. Param[3]¶
top left window corner vertical offset
9.1.2.5.19. CX2341X_OSD_SET_CHROMA_KEY¶
Enum: 96/0x60
9.1.2.5.19.1. Description¶
Chroma key switch and color
9.1.2.5.19.2. Param[0]¶
state: 0=off, 1=on
9.1.2.5.19.3. Param[1]¶
color
9.1.2.5.20. CX2341X_OSD_GET_ALPHA_CONTENT_INDEX¶
Enum: 97/0x61
9.1.2.5.20.1. Description¶
Retrieve alpha content index
9.1.2.5.20.2. Result[0]¶
alpha content index, Range 0:15
9.1.2.5.21. CX2341X_OSD_SET_ALPHA_CONTENT_INDEX¶
Enum: 98/0x62
9.1.2.5.21.1. Description¶
Assign alpha content index
9.1.2.5.21.2. Param[0]¶
alpha content index, range 0:15
9.1.2.6. Encoder firmware API description¶
9.1.2.6.1. CX2341X_ENC_PING_FW¶
Enum: 128/0x80
9.1.2.6.1.1. Description¶
Does nothing. Can be used to check if the firmware is responding.
9.1.2.6.2. CX2341X_ENC_START_CAPTURE¶
Enum: 129/0x81
9.1.2.6.2.1. Description¶
Commences the capture of video, audio and/or VBI data. All encoding parameters must be initialized prior to this API call. Captures frames continuously or until a predefined number of frames have been captured.
9.1.2.6.2.2. Param[0]¶
Capture stream type:
0=MPEG
1=Raw
2=Raw passthrough
3=VBI
9.1.2.6.2.3. Param[1]¶
Bitmask:
Bit 0 when set, captures YUV
Bit 1 when set, captures PCM audio
Bit 2 when set, captures VBI (same as param[0]=3)
Bit 3 when set, the capture destination is the decoder (same as param[0]=2)
Bit 4 when set, the capture destination is the host
Note
this parameter is only meaningful for RAW capture type.
9.1.2.6.3. CX2341X_ENC_STOP_CAPTURE¶
Enum: 130/0x82
9.1.2.6.3.1. Description¶
Ends a capture in progress
9.1.2.6.3.2. Param[0]¶
0=stop at end of GOP (generates IRQ)
1=stop immediate (no IRQ)
9.1.2.6.3.3. Param[1]¶
Stream type to stop, see param[0] of API 0x81
9.1.2.6.3.4. Param[2]¶
Subtype, see param[1] of API 0x81
9.1.2.6.4. CX2341X_ENC_SET_AUDIO_ID¶
Enum: 137/0x89
9.1.2.6.4.1. Description¶
Assigns the transport stream ID of the encoded audio stream
9.1.2.6.4.2. Param[0]¶
Audio Stream ID
9.1.2.6.5. CX2341X_ENC_SET_VIDEO_ID¶
Enum: 139/0x8B
9.1.2.6.5.1. Description¶
Set video transport stream ID
9.1.2.6.5.2. Param[0]¶
Video stream ID
9.1.2.6.6. CX2341X_ENC_SET_PCR_ID¶
Enum: 141/0x8D
9.1.2.6.6.1. Description¶
Assigns the transport stream ID for PCR packets
9.1.2.6.6.2. Param[0]¶
PCR Stream ID
9.1.2.6.7. CX2341X_ENC_SET_FRAME_RATE¶
Enum: 143/0x8F
9.1.2.6.7.1. Description¶
Set video frames per second. Change occurs at start of new GOP.
9.1.2.6.7.2. Param[0]¶
0=30fps
1=25fps
9.1.2.6.8. CX2341X_ENC_SET_FRAME_SIZE¶
Enum: 145/0x91
9.1.2.6.8.1. Description¶
Select video stream encoding resolution.
9.1.2.6.8.2. Param[0]¶
Height in lines. Default 480
9.1.2.6.8.3. Param[1]¶
Width in pixels. Default 720
9.1.2.6.9. CX2341X_ENC_SET_BIT_RATE¶
Enum: 149/0x95
9.1.2.6.9.1. Description¶
Assign average video stream bitrate.
9.1.2.6.9.2. Param[0]¶
0=variable bitrate, 1=constant bitrate
9.1.2.6.9.3. Param[1]¶
bitrate in bits per second
9.1.2.6.9.4. Param[2]¶
peak bitrate in bits per second, divided by 400
9.1.2.6.9.5. Param[3]¶
Mux bitrate in bits per second, divided by 400. May be 0 (default).
9.1.2.6.9.6. Param[4]¶
Rate Control VBR Padding
9.1.2.6.9.7. Param[5]¶
VBV Buffer used by encoder
Note
Param[3] and Param[4] seem to be always 0
Param[5] doesn’t seem to be used.
9.1.2.6.10. CX2341X_ENC_SET_GOP_PROPERTIES¶
Enum: 151/0x97
9.1.2.6.10.1. Description¶
Setup the GOP structure
9.1.2.6.10.2. Param[0]¶
GOP size (maximum is 34)
9.1.2.6.10.3. Param[1]¶
Number of B frames between the I and P frame, plus 1. For example: IBBPBBPBBPBB --> GOP size: 12, number of B frames: 2+1 = 3
Note
GOP size must be a multiple of (B-frames + 1).
9.1.2.6.11. CX2341X_ENC_SET_ASPECT_RATIO¶
Enum: 153/0x99
9.1.2.6.11.1. Description¶
Sets the encoding aspect ratio. Changes in the aspect ratio take effect at the start of the next GOP.
9.1.2.6.11.2. Param[0]¶
‘0000’ forbidden
‘0001’ 1:1 square
‘0010’ 4:3
‘0011’ 16:9
‘0100’ 2.21:1
‘0101’ to ‘1111’ reserved
9.1.2.6.12. CX2341X_ENC_SET_DNR_FILTER_MODE¶
Enum: 155/0x9B
9.1.2.6.12.1. Description¶
Assign Dynamic Noise Reduction operating mode
9.1.2.6.12.2. Param[0]¶
Bit0: Spatial filter, set=auto, clear=manual Bit1: Temporal filter, set=auto, clear=manual
9.1.2.6.12.3. Param[1]¶
Median filter:
0=Disabled
1=Horizontal
2=Vertical
3=Horiz/Vert
4=Diagonal
9.1.2.6.13. CX2341X_ENC_SET_DNR_FILTER_PROPS¶
Enum: 157/0x9D
9.1.2.6.13.1. Description¶
These Dynamic Noise Reduction filter values are only meaningful when the respective filter is set to “manual” (See API 0x9B)
9.1.2.6.13.2. Param[0]¶
Spatial filter: default 0, range 0:15
9.1.2.6.13.3. Param[1]¶
Temporal filter: default 0, range 0:31
9.1.2.6.14. CX2341X_ENC_SET_CORING_LEVELS¶
Enum: 159/0x9F
9.1.2.6.14.1. Description¶
Assign Dynamic Noise Reduction median filter properties.
9.1.2.6.14.2. Param[0]¶
Threshold above which the luminance median filter is enabled. Default: 0, range 0:255
9.1.2.6.14.3. Param[1]¶
Threshold below which the luminance median filter is enabled. Default: 255, range 0:255
9.1.2.6.14.4. Param[2]¶
Threshold above which the chrominance median filter is enabled. Default: 0, range 0:255
9.1.2.6.14.5. Param[3]¶
Threshold below which the chrominance median filter is enabled. Default: 255, range 0:255
9.1.2.6.15. CX2341X_ENC_SET_SPATIAL_FILTER_TYPE¶
Enum: 161/0xA1
9.1.2.6.15.1. Description¶
Assign spatial prefilter parameters
9.1.2.6.15.2. Param[0]¶
Luminance filter
0=Off
1=1D Horizontal
2=1D Vertical
3=2D H/V Separable (default)
4=2D Symmetric non-separable
9.1.2.6.15.3. Param[1]¶
Chrominance filter
0=Off
1=1D Horizontal (default)
9.1.2.6.16. CX2341X_ENC_SET_VBI_LINE¶
Enum: 183/0xB7
9.1.2.6.16.1. Description¶
Selects VBI line number.
9.1.2.6.16.2. Param[0]¶
Bits 0:4 line number
Bit 31 0=top_field, 1=bottom_field
Bits 0:31 all set specifies “all lines”
9.1.2.6.16.3. Param[1]¶
VBI line information features: 0=disabled, 1=enabled
9.1.2.6.16.4. Param[2]¶
Slicing: 0=None, 1=Closed Caption Almost certainly not implemented. Set to 0.
9.1.2.6.16.5. Param[3]¶
Luminance samples in this line. Almost certainly not implemented. Set to 0.
9.1.2.6.16.6. Param[4]¶
Chrominance samples in this line Almost certainly not implemented. Set to 0.
9.1.2.6.17. CX2341X_ENC_SET_STREAM_TYPE¶
Enum: 185/0xB9
9.1.2.6.17.1. Description¶
Assign stream type
Note
Transport stream is not working in recent firmwares. And in older firmwares the timestamps in the TS seem to be unreliable.
9.1.2.6.17.2. Param[0]¶
0=Program stream
1=Transport stream
2=MPEG1 stream
3=PES A/V stream
5=PES Video stream
7=PES Audio stream
10=DVD stream
11=VCD stream
12=SVCD stream
13=DVD_S1 stream
14=DVD_S2 stream
9.1.2.6.18. CX2341X_ENC_SET_OUTPUT_PORT¶
Enum: 187/0xBB
9.1.2.6.18.1. Description¶
Assign stream output port. Normally 0 when the data is copied through the PCI bus (DMA), and 1 when the data is streamed to another chip (pvrusb and cx88-blackbird).
9.1.2.6.18.2. Param[0]¶
0=Memory (default)
1=Streaming
2=Serial
9.1.2.6.18.3. Param[1]¶
Unknown, but leaving this to 0 seems to work best. Indications are that this might have to do with USB support, although passing anything but 0 only breaks things.
9.1.2.6.19. CX2341X_ENC_SET_AUDIO_PROPERTIES¶
Enum: 189/0xBD
9.1.2.6.19.1. Description¶
Set audio stream properties, may be called while encoding is in progress.
Note
All bitfields are consistent with ISO11172 documentation except bits 2:3 which ISO docs define as:
‘11’ Layer I
‘10’ Layer II
‘01’ Layer III
‘00’ Undefined
This discrepancy may indicate a possible error in the documentation. Testing indicated that only Layer II is actually working, and that the minimum bitrate should be 192 kbps.
9.1.2.6.19.2. Param[0]¶
Bitmask:
0:1 '00' 44.1Khz
'01' 48Khz
'10' 32Khz
'11' reserved
2:3 '01'=Layer I
'10'=Layer II
4:7 Bitrate:
Index | Layer I | Layer II
------+-------------+------------
'0000' | free format | free format
'0001' | 32 kbit/s | 32 kbit/s
'0010' | 64 kbit/s | 48 kbit/s
'0011' | 96 kbit/s | 56 kbit/s
'0100' | 128 kbit/s | 64 kbit/s
'0101' | 160 kbit/s | 80 kbit/s
'0110' | 192 kbit/s | 96 kbit/s
'0111' | 224 kbit/s | 112 kbit/s
'1000' | 256 kbit/s | 128 kbit/s
'1001' | 288 kbit/s | 160 kbit/s
'1010' | 320 kbit/s | 192 kbit/s
'1011' | 352 kbit/s | 224 kbit/s
'1100' | 384 kbit/s | 256 kbit/s
'1101' | 416 kbit/s | 320 kbit/s
'1110' | 448 kbit/s | 384 kbit/s
.. note::
For Layer II, not all combinations of total bitrate
and mode are allowed. See ISO11172-3 3-Annex B,
Table 3-B.2
8:9 '00'=Stereo
'01'=JointStereo
'10'=Dual
'11'=Mono
.. note::
The cx23415 cannot decode Joint Stereo properly.
10:11 Mode Extension used in joint_stereo mode.
In Layer I and II they indicate which subbands are in
intensity_stereo. All other subbands are coded in stereo.
'00' subbands 4-31 in intensity_stereo, bound==4
'01' subbands 8-31 in intensity_stereo, bound==8
'10' subbands 12-31 in intensity_stereo, bound==12
'11' subbands 16-31 in intensity_stereo, bound==16
12:13 Emphasis:
'00' None
'01' 50/15uS
'10' reserved
'11' CCITT J.17
14 CRC:
'0' off
'1' on
15 Copyright:
'0' off
'1' on
16 Generation:
'0' copy
'1' original
9.1.2.6.20. CX2341X_ENC_HALT_FW¶
Enum: 195/0xC3
9.1.2.6.20.1. Description¶
The firmware is halted and no further API calls are serviced until the firmware is uploaded again.
9.1.2.6.21. CX2341X_ENC_GET_VERSION¶
Enum: 196/0xC4
9.1.2.6.21.1. Description¶
Returns the version of the encoder firmware.
9.1.2.6.21.2. Result[0]¶
Version bitmask: - Bits 0:15 build - Bits 16:23 minor - Bits 24:31 major
9.1.2.6.22. CX2341X_ENC_SET_GOP_CLOSURE¶
Enum: 197/0xC5
9.1.2.6.22.1. Description¶
Assigns the GOP open/close property.
9.1.2.6.22.2. Param[0]¶
0=Open
1=Closed
9.1.2.6.23. CX2341X_ENC_GET_SEQ_END¶
Enum: 198/0xC6
9.1.2.6.23.1. Description¶
Obtains the sequence end code of the encoder’s buffer. When a capture is started a number of interrupts are still generated, the last of which will have Result[0] set to 1 and Result[1] will contain the size of the buffer.
9.1.2.6.23.2. Result[0]¶
State of the transfer (1 if last buffer)
9.1.2.6.23.3. Result[1]¶
If Result[0] is 1, this contains the size of the last buffer, undefined otherwise.
9.1.2.6.24. CX2341X_ENC_SET_PGM_INDEX_INFO¶
Enum: 199/0xC7
9.1.2.6.24.1. Description¶
Sets the Program Index Information. The information is stored as follows:
struct info {
u32 length; // Length of this frame
u32 offset_low; // Offset in the file of the
u32 offset_high; // start of this frame
u32 mask1; // Bits 0-2 are the type mask:
// 1=I, 2=P, 4=B
// 0=End of Program Index, other fields
// are invalid.
u32 pts; // The PTS of the frame
u32 mask2; // Bit 0 is bit 32 of the pts.
};
u32 table_ptr;
struct info index[400];
The table_ptr is the encoder memory address in the table were new entries will be written.
Note
This is a ringbuffer, so the table_ptr will wraparound.
9.1.2.6.24.2. Param[0]¶
Picture Mask: - 0=No index capture - 1=I frames - 3=I,P frames - 7=I,P,B frames
(Seems to be ignored, it always indexes I, P and B frames)
9.1.2.6.24.3. Param[1]¶
Elements requested (up to 400)
9.1.2.6.24.4. Result[0]¶
Offset in the encoder memory of the start of the table.
9.1.2.6.24.5. Result[1]¶
Number of allocated elements up to a maximum of Param[1]
9.1.2.6.25. CX2341X_ENC_SET_VBI_CONFIG¶
Enum: 200/0xC8
9.1.2.6.25.1. Description¶
Configure VBI settings
9.1.2.6.25.2. Param[0]¶
Bitmap:
0 Mode '0' Sliced, '1' Raw
1:3 Insertion:
'000' insert in extension & user data
'001' insert in private packets
'010' separate stream and user data
'111' separate stream and private data
8:15 Stream ID (normally 0xBD)
9.1.2.6.25.3. Param[1]¶
Frames per interrupt (max 8). Only valid in raw mode.
9.1.2.6.25.4. Param[2]¶
Total raw VBI frames. Only valid in raw mode.
9.1.2.6.25.5. Param[3]¶
Start codes
9.1.2.6.25.6. Param[4]¶
Stop codes
9.1.2.6.25.7. Param[5]¶
Lines per frame
9.1.2.6.25.8. Param[6]¶
Byte per line
9.1.2.6.25.9. Result[0]¶
Observed frames per interrupt in raw mode only. Rage 1 to Param[1]
9.1.2.6.25.10. Result[1]¶
Observed number of frames in raw mode. Range 1 to Param[2]
9.1.2.6.25.11. Result[2]¶
Memory offset to start or raw VBI data
9.1.2.6.26. CX2341X_ENC_SET_DMA_BLOCK_SIZE¶
Enum: 201/0xC9
9.1.2.6.26.1. Description¶
Set DMA transfer block size
9.1.2.6.26.2. Param[0]¶
DMA transfer block size in bytes or frames. When unit is bytes, supported block sizes are 2^7, 2^8 and 2^9 bytes.
9.1.2.6.26.3. Param[1]¶
Unit: 0=bytes, 1=frames
9.1.2.6.27. CX2341X_ENC_GET_PREV_DMA_INFO_MB_10¶
Enum: 202/0xCA
9.1.2.6.27.1. Description¶
Returns information on the previous DMA transfer in conjunction with bit 27 of the interrupt mask. Uses mailbox 10.
9.1.2.6.27.2. Result[0]¶
Type of stream
9.1.2.6.27.3. Result[1]¶
Address Offset
9.1.2.6.27.4. Result[2]¶
Maximum size of transfer
9.1.2.6.28. CX2341X_ENC_GET_PREV_DMA_INFO_MB_9¶
Enum: 203/0xCB
9.1.2.6.28.1. Description¶
Returns information on the previous DMA transfer in conjunction with bit 27 or 18 of the interrupt mask. Uses mailbox 9.
9.1.2.6.28.2. Result[0]¶
Status bits: - 0 read completed - 1 write completed - 2 DMA read error - 3 DMA write error - 4 Scatter-Gather array error
9.1.2.6.28.3. Result[1]¶
DMA type
9.1.2.6.28.4. Result[2]¶
Presentation Time Stamp bits 0..31
9.1.2.6.28.5. Result[3]¶
Presentation Time Stamp bit 32
9.1.2.6.29. CX2341X_ENC_SCHED_DMA_TO_HOST¶
Enum: 204/0xCC
9.1.2.6.29.1. Description¶
Setup DMA to host operation
9.1.2.6.29.2. Param[0]¶
Memory address of link list
9.1.2.6.29.3. Param[1]¶
Length of link list (wtf: what units ???)
9.1.2.6.29.4. Param[2]¶
DMA type (0=MPEG)
9.1.2.6.30. CX2341X_ENC_INITIALIZE_INPUT¶
Enum: 205/0xCD
9.1.2.6.30.1. Description¶
Initializes the video input
9.1.2.6.31. CX2341X_ENC_SET_FRAME_DROP_RATE¶
Enum: 208/0xD0
9.1.2.6.31.1. Description¶
For each frame captured, skip specified number of frames.
9.1.2.6.31.2. Param[0]¶
Number of frames to skip
9.1.2.6.32. CX2341X_ENC_PAUSE_ENCODER¶
Enum: 210/0xD2
9.1.2.6.32.1. Description¶
During a pause condition, all frames are dropped instead of being encoded.
9.1.2.6.32.2. Param[0]¶
0=Pause encoding
1=Continue encoding
9.1.2.6.33. CX2341X_ENC_REFRESH_INPUT¶
Enum: 211/0xD3
9.1.2.6.33.1. Description¶
Refreshes the video input
9.1.2.6.34. CX2341X_ENC_SET_COPYRIGHT¶
Enum: 212/0xD4
9.1.2.6.34.1. Description¶
Sets stream copyright property
9.1.2.6.34.2. Param[0]¶
0=Stream is not copyrighted
1=Stream is copyrighted
9.1.2.6.35. CX2341X_ENC_SET_EVENT_NOTIFICATION¶
Enum: 213/0xD5
9.1.2.6.35.1. Description¶
Setup firmware to notify the host about a particular event. Host must unmask the interrupt bit.
9.1.2.6.35.2. Param[0]¶
Event (0=refresh encoder input)
9.1.2.6.35.3. Param[1]¶
Notification 0=disabled 1=enabled
9.1.2.6.35.4. Param[2]¶
Interrupt bit
9.1.2.6.35.5. Param[3]¶
Mailbox slot, -1 if no mailbox required.
9.1.2.6.36. CX2341X_ENC_SET_NUM_VSYNC_LINES¶
Enum: 214/0xD6
9.1.2.6.36.1. Description¶
Depending on the analog video decoder used, this assigns the number of lines for field 1 and 2.
9.1.2.6.36.2. Param[0]¶
Field 1 number of lines: - 0x00EF for SAA7114 - 0x00F0 for SAA7115 - 0x0105 for Micronas
9.1.2.6.36.3. Param[1]¶
Field 2 number of lines: - 0x00EF for SAA7114 - 0x00F0 for SAA7115 - 0x0106 for Micronas
9.1.2.6.37. CX2341X_ENC_SET_PLACEHOLDER¶
Enum: 215/0xD7
9.1.2.6.37.1. Description¶
Provides a mechanism of inserting custom user data in the MPEG stream.
9.1.2.6.37.2. Param[0]¶
0=extension & user data
1=private packet with stream ID 0xBD
9.1.2.6.37.3. Param[1]¶
Rate at which to insert data, in units of frames (for private packet) or GOPs (for ext. & user data)
9.1.2.6.37.4. Param[2]¶
Number of data DWORDs (below) to insert
9.1.2.6.37.5. Param[3]¶
Custom data 0
9.1.2.6.37.6. Param[4]¶
Custom data 1
9.1.2.6.37.7. Param[5]¶
Custom data 2
9.1.2.6.37.8. Param[6]¶
Custom data 3
9.1.2.6.37.9. Param[7]¶
Custom data 4
9.1.2.6.37.10. Param[8]¶
Custom data 5
9.1.2.6.37.11. Param[9]¶
Custom data 6
9.1.2.6.37.12. Param[10]¶
Custom data 7
9.1.2.6.37.13. Param[11]¶
Custom data 8
9.1.2.6.38. CX2341X_ENC_MUTE_VIDEO¶
Enum: 217/0xD9
9.1.2.6.38.1. Description¶
Video muting
9.1.2.6.38.2. Param[0]¶
Bit usage:
0 '0'=video not muted
'1'=video muted, creates frames with the YUV color defined below
1:7 Unused
8:15 V chrominance information
16:23 U chrominance information
24:31 Y luminance information
9.1.2.6.39. CX2341X_ENC_MUTE_AUDIO¶
Enum: 218/0xDA
9.1.2.6.39.1. Description¶
Audio muting
9.1.2.6.39.2. Param[0]¶
0=audio not muted
1=audio muted (produces silent mpeg audio stream)
9.1.2.6.40. CX2341X_ENC_SET_VERT_CROP_LINE¶
Enum: 219/0xDB
9.1.2.6.40.1. Description¶
Something to do with ‘Vertical Crop Line’
9.1.2.6.40.2. Param[0]¶
If saa7114 and raw VBI capture and 60 Hz, then set to 10001. Else 0.
9.1.2.6.41. CX2341X_ENC_MISC¶
Enum: 220/0xDC
9.1.2.6.41.1. Description¶
Miscellaneous actions. Not known for 100% what it does. It’s really a sort of ioctl call. The first parameter is a command number, the second the value.
9.1.2.6.41.2. Param[0]¶
Command number:
1=set initial SCR value when starting encoding (works).
2=set quality mode (apparently some test setting).
3=setup advanced VIM protection handling.
Always 1 for the cx23416 and 0 for cx23415.
4=generate DVD compatible PTS timestamps
5=USB flush mode
6=something to do with the quantization matrix
7=set navigation pack insertion for DVD: adds 0xbf (private stream 2)
packets to the MPEG. The size of these packets is 2048 bytes (including
the header of 6 bytes: 0x000001bf + length). The payload is zeroed and
it is up to the application to fill them in. These packets are apparently
inserted every four frames.
8=enable scene change detection (seems to be a failure)
9=set history parameters of the video input module
10=set input field order of VIM
11=set quantization matrix
12=reset audio interface after channel change or input switch (has no argument).
Needed for the cx2584x, not needed for the mspx4xx, but it doesn't seem to
do any harm calling it regardless.
13=set audio volume delay
14=set audio delay
9.1.2.6.41.3. Param[1]¶
Command value.
9.1.2.7. Decoder firmware API description¶
Note
this API is part of the decoder firmware, so it’s cx23415 only.
9.1.2.7.1. CX2341X_DEC_PING_FW¶
Enum: 0/0x00
9.1.2.7.1.1. Description¶
This API call does nothing. It may be used to check if the firmware is responding.
9.1.2.7.2. CX2341X_DEC_START_PLAYBACK¶
Enum: 1/0x01
9.1.2.7.2.1. Description¶
Begin or resume playback.
9.1.2.7.2.2. Param[0]¶
0 based frame number in GOP to begin playback from.
9.1.2.7.2.3. Param[1]¶
Specifies the number of muted audio frames to play before normal audio resumes. (This is not implemented in the firmware, leave at 0)
9.1.2.7.3. CX2341X_DEC_STOP_PLAYBACK¶
Enum: 2/0x02
9.1.2.7.3.1. Description¶
Ends playback and clears all decoder buffers. If PTS is not zero, playback stops at specified PTS.
9.1.2.7.3.2. Param[0]¶
Display 0=last frame, 1=black
Note
this takes effect immediately, so if you want to wait for a PTS, then use ‘0’, otherwise the screen goes to black at once. You can call this later (even if there is no playback) with a 1 value to set the screen to black.
9.1.2.7.3.3. Param[1]¶
PTS low
9.1.2.7.3.4. Param[2]¶
PTS high
9.1.2.7.4. CX2341X_DEC_SET_PLAYBACK_SPEED¶
Enum: 3/0x03
9.1.2.7.4.1. Description¶
Playback stream at speed other than normal. There are two modes of operation:
Smooth: host transfers entire stream and firmware drops unused frames.
Coarse: host drops frames based on indexing as required to achieve desired speed.
9.1.2.7.4.2. Param[0]¶
Bitmap:
0:7 0 normal
1 fast only "1.5 times"
n nX fast, 1/nX slow
30 Framedrop:
'0' during 1.5 times play, every other B frame is dropped
'1' during 1.5 times play, stream is unchanged (bitrate
must not exceed 8mbps)
31 Speed:
'0' slow
'1' fast
Note
n is limited to 2. Anything higher does not result in faster playback. Instead the host should start dropping frames.
9.1.2.7.4.3. Param[1]¶
Direction: 0=forward, 1=reverse
Note
to make reverse playback work you have to write full GOPs in reverse order.
9.1.2.7.4.4. Param[2]¶
Picture mask:
1=I frames
3=I, P frames
7=I, P, B frames
9.1.2.7.4.5. Param[3]¶
B frames per GOP (for reverse play only)
Note
for reverse playback the Picture Mask should be set to I or I, P. Adding B frames to the mask will result in corrupt video. This field has to be set to the correct value in order to keep the timing correct.
9.1.2.7.4.6. Param[4]¶
Mute audio: 0=disable, 1=enable
9.1.2.7.4.7. Param[5]¶
Display 0=frame, 1=field
9.1.2.7.4.8. Param[6]¶
Specifies the number of muted audio frames to play before normal audio resumes. (Not implemented in the firmware, leave at 0)
9.1.2.7.5. CX2341X_DEC_STEP_VIDEO¶
Enum: 5/0x05
9.1.2.7.5.1. Description¶
Each call to this API steps the playback to the next unit defined below in the current playback direction.
9.1.2.7.5.2. Param[0]¶
0=frame, 1=top field, 2=bottom field
9.1.2.7.6. CX2341X_DEC_SET_DMA_BLOCK_SIZE¶
Enum: 8/0x08
9.1.2.7.6.1. Description¶
Set DMA transfer block size. Counterpart to API 0xC9
9.1.2.7.6.2. Param[0]¶
DMA transfer block size in bytes. A different size may be specified when issuing the DMA transfer command.
9.1.2.7.7. CX2341X_DEC_GET_XFER_INFO¶
Enum: 9/0x09
9.1.2.7.7.1. Description¶
This API call may be used to detect an end of stream condition.
9.1.2.7.7.2. Result[0]¶
Stream type
9.1.2.7.7.3. Result[1]¶
Address offset
9.1.2.7.7.4. Result[2]¶
Maximum bytes to transfer
9.1.2.7.7.5. Result[3]¶
Buffer fullness
9.1.2.7.8. CX2341X_DEC_GET_DMA_STATUS¶
Enum: 10/0x0A
9.1.2.7.8.1. Description¶
Status of the last DMA transfer
9.1.2.7.8.2. Result[0]¶
Bit 1 set means transfer complete Bit 2 set means DMA error Bit 3 set means linked list error
9.1.2.7.8.3. Result[1]¶
DMA type: 0=MPEG, 1=OSD, 2=YUV
9.1.2.7.9. CX2341X_DEC_SCHED_DMA_FROM_HOST¶
Enum: 11/0x0B
9.1.2.7.9.1. Description¶
Setup DMA from host operation. Counterpart to API 0xCC
9.1.2.7.9.2. Param[0]¶
Memory address of link list
9.1.2.7.9.3. Param[1]¶
Total # of bytes to transfer
9.1.2.7.9.4. Param[2]¶
DMA type (0=MPEG, 1=OSD, 2=YUV)
9.1.2.7.10. CX2341X_DEC_PAUSE_PLAYBACK¶
Enum: 13/0x0D
9.1.2.7.10.1. Description¶
Freeze playback immediately. In this mode, when internal buffers are full, no more data will be accepted and data request IRQs will be masked.
9.1.2.7.10.2. Param[0]¶
Display: 0=last frame, 1=black
9.1.2.7.11. CX2341X_DEC_HALT_FW¶
Enum: 14/0x0E
9.1.2.7.11.1. Description¶
The firmware is halted and no further API calls are serviced until the firmware is uploaded again.
9.1.2.7.12. CX2341X_DEC_SET_STANDARD¶
Enum: 16/0x10
9.1.2.7.12.1. Description¶
Selects display standard
9.1.2.7.12.2. Param[0]¶
0=NTSC, 1=PAL
9.1.2.7.13. CX2341X_DEC_GET_VERSION¶
Enum: 17/0x11
9.1.2.7.13.1. Description¶
Returns decoder firmware version information
9.1.2.7.13.2. Result[0]¶
- Version bitmask:
Bits 0:15 build
Bits 16:23 minor
Bits 24:31 major
9.1.2.7.14. CX2341X_DEC_SET_STREAM_INPUT¶
Enum: 20/0x14
9.1.2.7.14.1. Description¶
Select decoder stream input port
9.1.2.7.14.2. Param[0]¶
0=memory (default), 1=streaming
9.1.2.7.15. CX2341X_DEC_GET_TIMING_INFO¶
Enum: 21/0x15
9.1.2.7.15.1. Description¶
Returns timing information from start of playback
9.1.2.7.15.2. Result[0]¶
Frame count by decode order
9.1.2.7.15.3. Result[1]¶
Video PTS bits 0:31 by display order
9.1.2.7.15.4. Result[2]¶
Video PTS bit 32 by display order
9.1.2.7.15.5. Result[3]¶
SCR bits 0:31 by display order
9.1.2.7.15.6. Result[4]¶
SCR bit 32 by display order
9.1.2.7.16. CX2341X_DEC_SET_AUDIO_MODE¶
Enum: 22/0x16
9.1.2.7.16.1. Description¶
Select audio mode
9.1.2.7.16.2. Param[0]¶
- Dual mono mode action
0=Stereo, 1=Left, 2=Right, 3=Mono, 4=Swap, -1=Unchanged
9.1.2.7.16.3. Param[1]¶
- Stereo mode action:
0=Stereo, 1=Left, 2=Right, 3=Mono, 4=Swap, -1=Unchanged
9.1.2.7.17. CX2341X_DEC_SET_EVENT_NOTIFICATION¶
Enum: 23/0x17
9.1.2.7.17.1. Description¶
Setup firmware to notify the host about a particular event. Counterpart to API 0xD5
9.1.2.7.17.2. Param[0]¶
- Event:
0=Audio mode change between mono, (joint) stereo and dual channel.
3=Decoder started
4=Unknown: goes off 10-15 times per second while decoding.
5=Some sync event: goes off once per frame.
9.1.2.7.17.3. Param[1]¶
Notification 0=disabled, 1=enabled
9.1.2.7.17.4. Param[2]¶
Interrupt bit
9.1.2.7.17.5. Param[3]¶
Mailbox slot, -1 if no mailbox required.
9.1.2.7.18. CX2341X_DEC_SET_DISPLAY_BUFFERS¶
Enum: 24/0x18
9.1.2.7.18.1. Description¶
Number of display buffers. To decode all frames in reverse playback you must use nine buffers.
9.1.2.7.18.2. Param[0]¶
0=six buffers, 1=nine buffers
9.1.2.7.19. CX2341X_DEC_EXTRACT_VBI¶
Enum: 25/0x19
9.1.2.7.19.1. Description¶
Extracts VBI data
9.1.2.7.19.2. Param[0]¶
0=extract from extension & user data, 1=extract from private packets
9.1.2.7.19.3. Result[0]¶
VBI table location
9.1.2.7.19.4. Result[1]¶
VBI table size
9.1.2.7.20. CX2341X_DEC_SET_DECODER_SOURCE¶
Enum: 26/0x1A
9.1.2.7.20.1. Description¶
Selects decoder source. Ensure that the parameters passed to this API match the encoder settings.
9.1.2.7.20.2. Param[0]¶
Mode: 0=MPEG from host, 1=YUV from encoder, 2=YUV from host
9.1.2.7.20.3. Param[1]¶
YUV picture width
9.1.2.7.20.4. Param[2]¶
YUV picture height
9.1.2.7.20.5. Param[3]¶
Bitmap: see Param[0] of API 0xBD
9.1.2.7.21. CX2341X_DEC_SET_PREBUFFERING¶
Enum: 30/0x1E
9.1.2.7.21.1. Description¶
Decoder prebuffering, when enabled up to 128KB are buffered for streams <8mpbs or 640KB for streams >8mbps
9.1.2.7.21.2. Param[0]¶
0=off, 1=on
9.1.2.8. PVR350 Video decoder registers 0x02002800 -> 0x02002B00¶
Author: Ian Armstrong <ian@iarmst.demon.co.uk>
Version: v0.4
Date: 12 March 2007
This list has been worked out through trial and error. There will be mistakes and omissions. Some registers have no obvious effect so it’s hard to say what they do, while others interact with each other, or require a certain load sequence. Horizontal filter setup is one example, with six registers working in unison and requiring a certain load sequence to correctly configure. The indexed colour palette is much easier to set at just two registers, but again it requires a certain load sequence.
Some registers are fussy about what they are set to. Load in a bad value & the decoder will fail. A firmware reload will often recover, but sometimes a reset is required. For registers containing size information, setting them to 0 is generally a bad idea. For other control registers i.e. 2878, you’ll only find out what values are bad when it hangs.
--------------------------------------------------------------------------------
2800
bit 0
Decoder enable
0 = disable
1 = enable
--------------------------------------------------------------------------------
2804
bits 0:31
Decoder horizontal Y alias register 1
---------------
2808
bits 0:31
Decoder horizontal Y alias register 2
---------------
280C
bits 0:31
Decoder horizontal Y alias register 3
---------------
2810
bits 0:31
Decoder horizontal Y alias register 4
---------------
2814
bits 0:31
Decoder horizontal Y alias register 5
---------------
2818
bits 0:31
Decoder horizontal Y alias trigger
These six registers control the horizontal aliasing filter for the Y plane.
The first five registers must all be loaded before accessing the trigger
(2818), as this register actually clocks the data through for the first
five.
To correctly program set the filter, this whole procedure must be done 16
times. The actual register contents are copied from a lookup-table in the
firmware which contains 4 different filter settings.
--------------------------------------------------------------------------------
281C
bits 0:31
Decoder horizontal UV alias register 1
---------------
2820
bits 0:31
Decoder horizontal UV alias register 2
---------------
2824
bits 0:31
Decoder horizontal UV alias register 3
---------------
2828
bits 0:31
Decoder horizontal UV alias register 4
---------------
282C
bits 0:31
Decoder horizontal UV alias register 5
---------------
2830
bits 0:31
Decoder horizontal UV alias trigger
These six registers control the horizontal aliasing for the UV plane.
Operation is the same as the Y filter, with 2830 being the trigger
register.
--------------------------------------------------------------------------------
2834
bits 0:15
Decoder Y source width in pixels
bits 16:31
Decoder Y destination width in pixels
---------------
2838
bits 0:15
Decoder UV source width in pixels
bits 16:31
Decoder UV destination width in pixels
NOTE: For both registers, the resulting image must be fully visible on
screen. If the image exceeds the right edge both the source and destination
size must be adjusted to reflect the visible portion. For the source width,
you must take into account the scaling when calculating the new value.
--------------------------------------------------------------------------------
283C
bits 0:31
Decoder Y horizontal scaling
Normally = Reg 2854 >> 2
---------------
2840
bits 0:31
Decoder ?? unknown - horizontal scaling
Usually 0x00080514
---------------
2844
bits 0:31
Decoder UV horizontal scaling
Normally = Reg 2854 >> 2
---------------
2848
bits 0:31
Decoder ?? unknown - horizontal scaling
Usually 0x00100514
---------------
284C
bits 0:31
Decoder ?? unknown - Y plane
Usually 0x00200020
---------------
2850
bits 0:31
Decoder ?? unknown - UV plane
Usually 0x00200020
---------------
2854
bits 0:31
Decoder 'master' value for horizontal scaling
---------------
2858
bits 0:31
Decoder ?? unknown
Usually 0
---------------
285C
bits 0:31
Decoder ?? unknown
Normally = Reg 2854 >> 1
---------------
2860
bits 0:31
Decoder ?? unknown
Usually 0
---------------
2864
bits 0:31
Decoder ?? unknown
Normally = Reg 2854 >> 1
---------------
2868
bits 0:31
Decoder ?? unknown
Usually 0
Most of these registers either control horizontal scaling, or appear linked
to it in some way. Register 2854 contains the 'master' value & the other
registers can be calculated from that one. You must also remember to
correctly set the divider in Reg 2874.
To enlarge:
Reg 2854 = (source_width * 0x00200000) / destination_width
Reg 2874 = No divide
To reduce from full size down to half size:
Reg 2854 = (source_width/2 * 0x00200000) / destination width
Reg 2874 = Divide by 2
To reduce from half size down to quarter size:
Reg 2854 = (source_width/4 * 0x00200000) / destination width
Reg 2874 = Divide by 4
The result is always rounded up.
--------------------------------------------------------------------------------
286C
bits 0:15
Decoder horizontal Y buffer offset
bits 15:31
Decoder horizontal UV buffer offset
Offset into the video image buffer. If the offset is gradually incremented,
the on screen image will move left & wrap around higher up on the right.
--------------------------------------------------------------------------------
2870
bits 0:15
Decoder horizontal Y output offset
bits 16:31
Decoder horizontal UV output offset
Offsets the actual video output. Controls output alignment of the Y & UV
planes. The higher the value, the greater the shift to the left. Use
reg 2890 to move the image right.
--------------------------------------------------------------------------------
2874
bits 0:1
Decoder horizontal Y output size divider
00 = No divide
01 = Divide by 2
10 = Divide by 3
bits 4:5
Decoder horizontal UV output size divider
00 = No divide
01 = Divide by 2
10 = Divide by 3
bit 8
Decoder ?? unknown
0 = Normal
1 = Affects video output levels
bit 16
Decoder ?? unknown
0 = Normal
1 = Disable horizontal filter
--------------------------------------------------------------------------------
2878
bit 0
?? unknown
bit 1
osd on/off
0 = osd off
1 = osd on
bit 2
Decoder + osd video timing
0 = NTSC
1 = PAL
bits 3:4
?? unknown
bit 5
Decoder + osd
Swaps upper & lower fields
--------------------------------------------------------------------------------
287C
bits 0:10
Decoder & osd ?? unknown
Moves entire screen horizontally. Starts at 0x005 with the screen
shifted heavily to the right. Incrementing in steps of 0x004 will
gradually shift the screen to the left.
bits 11:31
?? unknown
Normally contents are 0x00101111 (NTSC) or 0x1010111d (PAL)
--------------------------------------------------------------------------------
2880 -------- ?? unknown
2884 -------- ?? unknown
--------------------------------------------------------------------------------
2888
bit 0
Decoder + osd ?? unknown
0 = Normal
1 = Misaligned fields (Correctable through 289C & 28A4)
bit 4
?? unknown
bit 8
?? unknown
Warning: Bad values will require a firmware reload to recover.
Known to be bad are 0x000,0x011,0x100,0x111
--------------------------------------------------------------------------------
288C
bits 0:15
osd ?? unknown
Appears to affect the osd position stability. The higher the value the
more unstable it becomes. Decoder output remains stable.
bits 16:31
osd ?? unknown
Same as bits 0:15
--------------------------------------------------------------------------------
2890
bits 0:11
Decoder output horizontal offset.
Horizontal offset moves the video image right. A small left shift is
possible, but it's better to use reg 2870 for that due to its greater
range.
NOTE: Video corruption will occur if video window is shifted off the right
edge. To avoid this read the notes for 2834 & 2838.
--------------------------------------------------------------------------------
2894
bits 0:23
Decoder output video surround colour.
Contains the colour (in yuv) used to fill the screen when the video is
running in a window.
--------------------------------------------------------------------------------
2898
bits 0:23
Decoder video window colour
Contains the colour (in yuv) used to fill the video window when the
video is turned off.
bit 24
Decoder video output
0 = Video on
1 = Video off
bit 28
Decoder plane order
0 = Y,UV
1 = UV,Y
bit 29
Decoder second plane byte order
0 = Normal (UV)
1 = Swapped (VU)
In normal usage, the first plane is Y & the second plane is UV. Though the
order of the planes can be swapped, only the byte order of the second plane
can be swapped. This isn't much use for the Y plane, but can be useful for
the UV plane.
--------------------------------------------------------------------------------
289C
bits 0:15
Decoder vertical field offset 1
bits 16:31
Decoder vertical field offset 2
Controls field output vertical alignment. The higher the number, the lower
the image on screen. Known starting values are 0x011E0017 (NTSC) &
0x01500017 (PAL)
--------------------------------------------------------------------------------
28A0
bits 0:15
Decoder & osd width in pixels
bits 16:31
Decoder & osd height in pixels
All output from the decoder & osd are disabled beyond this area. Decoder
output will simply go black outside of this region. If the osd tries to
exceed this area it will become corrupt.
--------------------------------------------------------------------------------
28A4
bits 0:11
osd left shift.
Has a range of 0x770->0x7FF. With the exception of 0, any value outside of
this range corrupts the osd.
--------------------------------------------------------------------------------
28A8
bits 0:15
osd vertical field offset 1
bits 16:31
osd vertical field offset 2
Controls field output vertical alignment. The higher the number, the lower
the image on screen. Known starting values are 0x011E0017 (NTSC) &
0x01500017 (PAL)
--------------------------------------------------------------------------------
28AC -------- ?? unknown
|
V
28BC -------- ?? unknown
--------------------------------------------------------------------------------
28C0
bit 0
Current output field
0 = first field
1 = second field
bits 16:31
Current scanline
The scanline counts from the top line of the first field
through to the last line of the second field.
--------------------------------------------------------------------------------
28C4 -------- ?? unknown
|
V
28F8 -------- ?? unknown
--------------------------------------------------------------------------------
28FC
bit 0
?? unknown
0 = Normal
1 = Breaks decoder & osd output
--------------------------------------------------------------------------------
2900
bits 0:31
Decoder vertical Y alias register 1
---------------
2904
bits 0:31
Decoder vertical Y alias register 2
---------------
2908
bits 0:31
Decoder vertical Y alias trigger
These three registers control the vertical aliasing filter for the Y plane.
Operation is similar to the horizontal Y filter (2804). The only real
difference is that there are only two registers to set before accessing
the trigger register (2908). As for the horizontal filter, the values are
taken from a lookup table in the firmware, and the procedure must be
repeated 16 times to fully program the filter.
--------------------------------------------------------------------------------
290C
bits 0:31
Decoder vertical UV alias register 1
---------------
2910
bits 0:31
Decoder vertical UV alias register 2
---------------
2914
bits 0:31
Decoder vertical UV alias trigger
These three registers control the vertical aliasing filter for the UV
plane. Operation is the same as the Y filter, with 2914 being the trigger.
--------------------------------------------------------------------------------
2918
bits 0:15
Decoder Y source height in pixels
bits 16:31
Decoder Y destination height in pixels
---------------
291C
bits 0:15
Decoder UV source height in pixels divided by 2
bits 16:31
Decoder UV destination height in pixels
NOTE: For both registers, the resulting image must be fully visible on
screen. If the image exceeds the bottom edge both the source and
destination size must be adjusted to reflect the visible portion. For the
source height, you must take into account the scaling when calculating the
new value.
--------------------------------------------------------------------------------
2920
bits 0:31
Decoder Y vertical scaling
Normally = Reg 2930 >> 2
---------------
2924
bits 0:31
Decoder Y vertical scaling
Normally = Reg 2920 + 0x514
---------------
2928
bits 0:31
Decoder UV vertical scaling
When enlarging = Reg 2930 >> 2
When reducing = Reg 2930 >> 3
---------------
292C
bits 0:31
Decoder UV vertical scaling
Normally = Reg 2928 + 0x514
---------------
2930
bits 0:31
Decoder 'master' value for vertical scaling
---------------
2934
bits 0:31
Decoder ?? unknown - Y vertical scaling
---------------
2938
bits 0:31
Decoder Y vertical scaling
Normally = Reg 2930
---------------
293C
bits 0:31
Decoder ?? unknown - Y vertical scaling
---------------
2940
bits 0:31
Decoder UV vertical scaling
When enlarging = Reg 2930 >> 1
When reducing = Reg 2930
---------------
2944
bits 0:31
Decoder ?? unknown - UV vertical scaling
---------------
2948
bits 0:31
Decoder UV vertical scaling
Normally = Reg 2940
---------------
294C
bits 0:31
Decoder ?? unknown - UV vertical scaling
Most of these registers either control vertical scaling, or appear linked
to it in some way. Register 2930 contains the 'master' value & all other
registers can be calculated from that one. You must also remember to
correctly set the divider in Reg 296C
To enlarge:
Reg 2930 = (source_height * 0x00200000) / destination_height
Reg 296C = No divide
To reduce from full size down to half size:
Reg 2930 = (source_height/2 * 0x00200000) / destination height
Reg 296C = Divide by 2
To reduce from half down to quarter.
Reg 2930 = (source_height/4 * 0x00200000) / destination height
Reg 296C = Divide by 4
--------------------------------------------------------------------------------
2950
bits 0:15
Decoder Y line index into display buffer, first field
bits 16:31
Decoder Y vertical line skip, first field
--------------------------------------------------------------------------------
2954
bits 0:15
Decoder Y line index into display buffer, second field
bits 16:31
Decoder Y vertical line skip, second field
--------------------------------------------------------------------------------
2958
bits 0:15
Decoder UV line index into display buffer, first field
bits 16:31
Decoder UV vertical line skip, first field
--------------------------------------------------------------------------------
295C
bits 0:15
Decoder UV line index into display buffer, second field
bits 16:31
Decoder UV vertical line skip, second field
--------------------------------------------------------------------------------
2960
bits 0:15
Decoder destination height minus 1
bits 16:31
Decoder destination height divided by 2
--------------------------------------------------------------------------------
2964
bits 0:15
Decoder Y vertical offset, second field
bits 16:31
Decoder Y vertical offset, first field
These two registers shift the Y plane up. The higher the number, the
greater the shift.
--------------------------------------------------------------------------------
2968
bits 0:15
Decoder UV vertical offset, second field
bits 16:31
Decoder UV vertical offset, first field
These two registers shift the UV plane up. The higher the number, the
greater the shift.
--------------------------------------------------------------------------------
296C
bits 0:1
Decoder vertical Y output size divider
00 = No divide
01 = Divide by 2
10 = Divide by 4
bits 8:9
Decoder vertical UV output size divider
00 = No divide
01 = Divide by 2
10 = Divide by 4
--------------------------------------------------------------------------------
2970
bit 0
Decoder ?? unknown
0 = Normal
1 = Affect video output levels
bit 16
Decoder ?? unknown
0 = Normal
1 = Disable vertical filter
--------------------------------------------------------------------------------
2974 -------- ?? unknown
|
V
29EF -------- ?? unknown
--------------------------------------------------------------------------------
2A00
bits 0:2
osd colour mode
000 = 8 bit indexed
001 = 16 bit (565)
010 = 15 bit (555)
011 = 12 bit (444)
100 = 32 bit (8888)
bits 4:5
osd display bpp
01 = 8 bit
10 = 16 bit
11 = 32 bit
bit 8
osd global alpha
0 = Off
1 = On
bit 9
osd local alpha
0 = Off
1 = On
bit 10
osd colour key
0 = Off
1 = On
bit 11
osd ?? unknown
Must be 1
bit 13
osd colour space
0 = ARGB
1 = AYVU
bits 16:31
osd ?? unknown
Must be 0x001B (some kind of buffer pointer ?)
When the bits-per-pixel is set to 8, the colour mode is ignored and
assumed to be 8 bit indexed. For 16 & 32 bits-per-pixel the colour depth
is honoured, and when using a colour depth that requires fewer bytes than
allocated the extra bytes are used as padding. So for a 32 bpp with 8 bit
index colour, there are 3 padding bytes per pixel. It's also possible to
select 16bpp with a 32 bit colour mode. This results in the pixel width
being doubled, but the color key will not work as expected in this mode.
Colour key is as it suggests. You designate a colour which will become
completely transparent. When using 565, 555 or 444 colour modes, the
colour key is always 16 bits wide. The colour to key on is set in Reg 2A18.
Local alpha works differently depending on the colour mode. For 32bpp & 8
bit indexed, local alpha is a per-pixel 256 step transparency, with 0 being
transparent and 255 being solid. For the 16bpp modes 555 & 444, the unused
bit(s) act as a simple transparency switch, with 0 being solid & 1 being
fully transparent. There is no local alpha support for 16bit 565.
Global alpha is a 256 step transparency that applies to the entire osd,
with 0 being transparent & 255 being solid.
It's possible to combine colour key, local alpha & global alpha.
--------------------------------------------------------------------------------
2A04
bits 0:15
osd x coord for left edge
bits 16:31
osd y coord for top edge
---------------
2A08
bits 0:15
osd x coord for right edge
bits 16:31
osd y coord for bottom edge
For both registers, (0,0) = top left corner of the display area. These
registers do not control the osd size, only where it's positioned & how
much is visible. The visible osd area cannot exceed the right edge of the
display, otherwise the osd will become corrupt. See reg 2A10 for
setting osd width.
--------------------------------------------------------------------------------
2A0C
bits 0:31
osd buffer index
An index into the osd buffer. Slowly incrementing this moves the osd left,
wrapping around onto the right edge
--------------------------------------------------------------------------------
2A10
bits 0:11
osd buffer 32 bit word width
Contains the width of the osd measured in 32 bit words. This means that all
colour modes are restricted to a byte width which is divisible by 4.
--------------------------------------------------------------------------------
2A14
bits 0:15
osd height in pixels
bits 16:32
osd line index into buffer
osd will start displaying from this line.
--------------------------------------------------------------------------------
2A18
bits 0:31
osd colour key
Contains the colour value which will be transparent.
--------------------------------------------------------------------------------
2A1C
bits 0:7
osd global alpha
Contains the global alpha value (equiv ivtvfbctl --alpha XX)
--------------------------------------------------------------------------------
2A20 -------- ?? unknown
|
V
2A2C -------- ?? unknown
--------------------------------------------------------------------------------
2A30
bits 0:7
osd colour to change in indexed palette
---------------
2A34
bits 0:31
osd colour for indexed palette
To set the new palette, first load the index of the colour to change into
2A30, then load the new colour into 2A34. The full palette is 256 colours,
so the index range is 0x00-0xFF
--------------------------------------------------------------------------------
2A38 -------- ?? unknown
2A3C -------- ?? unknown
--------------------------------------------------------------------------------
2A40
bits 0:31
osd ?? unknown
Affects overall brightness, wrapping around to black
--------------------------------------------------------------------------------
2A44
bits 0:31
osd ?? unknown
Green tint
--------------------------------------------------------------------------------
2A48
bits 0:31
osd ?? unknown
Red tint
--------------------------------------------------------------------------------
2A4C
bits 0:31
osd ?? unknown
Affects overall brightness, wrapping around to black
--------------------------------------------------------------------------------
2A50
bits 0:31
osd ?? unknown
Colour shift
--------------------------------------------------------------------------------
2A54
bits 0:31
osd ?? unknown
Colour shift
--------------------------------------------------------------------------------
2A58 -------- ?? unknown
|
V
2AFC -------- ?? unknown
--------------------------------------------------------------------------------
2B00
bit 0
osd filter control
0 = filter off
1 = filter on
bits 1:4
osd ?? unknown
--------------------------------------------------------------------------------
9.1.2.9. The cx231xx DMA engine¶
This page describes the structures and procedures used by the cx2341x DMA engine.
9.1.2.9.1. Introduction¶
The cx2341x PCI interface is busmaster capable. This means it has a DMA engine to efficiently transfer large volumes of data between the card and main memory without requiring help from a CPU. Like most hardware, it must operate on contiguous physical memory. This is difficult to come by in large quantities on virtual memory machines.
Therefore, it also supports a technique called “scatter-gather”. The card can transfer multiple buffers in one operation. Instead of allocating one large contiguous buffer, the driver can allocate several smaller buffers.
In practice, I’ve seen the average transfer to be roughly 80K, but transfers above 128K were not uncommon, particularly at startup. The 128K figure is important, because that is the largest block that the kernel can normally allocate. Even still, 128K blocks are hard to come by, so the driver writer is urged to choose a smaller block size and learn the scatter-gather technique.
Mailbox #10 is reserved for DMA transfer information.
Note: the hardware expects little-endian data (‘intel format’).
9.1.2.9.2. Flow¶
This section describes, in general, the order of events when handling DMA transfers. Detailed information follows this section.
The card raises the Encoder interrupt.
The driver reads the transfer type, offset and size from Mailbox #10.
The driver constructs the scatter-gather array from enough free dma buffers to cover the size.
The driver schedules the DMA transfer via the ScheduleDMAtoHost API call.
The card raises the DMA Complete interrupt.
The driver checks the DMA status register for any errors.
The driver post-processes the newly transferred buffers.
NOTE! It is possible that the Encoder and DMA Complete interrupts get raised simultaneously. (End of the last, start of the next, etc.)
9.1.2.9.3. Mailbox #10¶
The Flags, Command, Return Value and Timeout fields are ignored.
Name: Mailbox #10
Results[0]: Type: 0: MPEG.
Results[1]: Offset: The position relative to the card’s memory space.
Results[2]: Size: The exact number of bytes to transfer.
My speculation is that since the StartCapture API has a capture type of “RAW” available, that the type field will have other values that correspond to YUV and PCM data.
9.1.2.9.4. Scatter-Gather Array¶
The scatter-gather array is a contiguously allocated block of memory that tells the card the source and destination of each data-block to transfer. Card “addresses” are derived from the offset supplied by Mailbox #10. Host addresses are the physical memory location of the target DMA buffer.
Each S-G array element is a struct of three 32-bit words. The first word is the source address, the second is the destination address. Both take up the entire 32 bits. The lowest 18 bits of the third word is the transfer byte count. The high-bit of the third word is the “last” flag. The last-flag tells the card to raise the DMA_DONE interrupt. From hard personal experience, if you forget to set this bit, the card will still “work” but the stream will most likely get corrupted.
The transfer count must be a multiple of 256. Therefore, the driver will need to track how much data in the target buffer is valid and deal with it accordingly.
Array Element:
32-bit Source Address
32-bit Destination Address
14-bit reserved (high bit is the last flag)
18-bit byte count
9.1.2.9.5. DMA Transfer Status¶
Register 0x0004 holds the DMA Transfer Status:
bit 0: read completed
bit 1: write completed
bit 2: DMA read error
bit 3: DMA write error
bit 4: Scatter-Gather array error