* Problematic Alt Setting for ALi Corp. Newmine Camera. (plaintext)
@ 2023-10-19 9:15 Karel Janda
2023-10-19 22:24 ` Laurent Pinchart
0 siblings, 1 reply; 2+ messages in thread
From: Karel Janda @ 2023-10-19 9:15 UTC (permalink / raw)
To: Laurent Pinchart; +Cc: Linux Media
[-- Attachment #1: Type: text/plain, Size: 1548 bytes --]
Hi,
in my class I use ten C-TECH CAM-07HD cameras, detected as
ID 0402:8841 ALi Corp. Newmine Camera.
The camera works OK with resolutions <= 320x240@60fps.
Bigger MJPEG resolutions were laggy, with lots of errors in kern.log:
usb 1-2: USB isochronous frame lost (-75)
xhci_hcd 0000:15:00.0: WARN: buffer overrun event for slot 9 ep 4 on endpoint
Bigger YUY2 resolutions did not get any data. Quirks doesn't help.
Behavior is the same on (Ubuntu) kernels 6.5.0, 6.2.0, 5.4.0,
both on 2.0 and 3.0 USB ports.
So I start USB scanning and finally find the reason:
- camera sends four isochronous interface descriptors for wMaxPacketSize 1024 bytes
and linux uvcvideo module always chooses bAlternateSetting 4.
- Windows 10 always chooses bAlternateSetting 1 for the camera
and bigger resolutions are working OK there.
(I attached listing from lspci -v -d 0402:8841 )
This original line of code from drivers/media/usb/uvc/uvc_video.c
if (psize >= bandwidth && psize <= best_psize) {
chooses last alt setting in case the same wMaxPacketSize values.
If I force using settings 1, 2 or 3 instead in uvc_video.c,
my REALLY BAD camera starts working OK like a charm, without log errors.
So I offer you to change the line above in some future uvc_video.c to:
if (psize >= bandwidth && psize < best_psize) { //first preferency
which I probe completely solved this problem
and as Windows does the same will not harm other types of cameras.
sincerely
Karel Janda
[-- Attachment #2: ctech.lst --]
[-- Type: application/octet-stream, Size: 31065 bytes --]
Bus 001 Device 007: ID 0402:8841 ALi Corp. Newmine Camera
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
idVendor 0x0402 ALi Corp.
idProduct 0x8841
bcdDevice 0.01
iManufacturer 1
iProduct 2
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x04d0
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 0
iInterface 4
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 0x004f
dwClockFrequency 30.000000MHz
bInCollection 1
baInterfaceNr( 0) 1
VideoControl Interface Descriptor:
bLength 28
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 6
guidExtensionCode {68bbd0b0-61a4-4b83-90b7-a6215f3c4f70}
bNumControl 24
bNrPins 1
baSourceID( 0) 2
bControlSize 3
bmControls( 0) 0xff
bmControls( 1) 0xff
bmControls( 2) 0xff
iExtension 0
VideoControl Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Camera Sensor
bAssocTerminal 0
iTerminal 0
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 3
bmControls 0x00000000
VideoControl Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 5 (PROCESSING_UNIT)
Warning: Descriptor too short
bUnitID 2
bSourceID 1
wMaxMultiplier 0
bControlSize 2
bmControls 0x0000157f
Brightness
Contrast
Hue
Saturation
Sharpness
Gamma
White Balance Temperature
Backlight Compensation
Power Line Frequency
White Balance Temperature, Auto
iProcessing 0
bmVideoStandards 0x09
None
SECAM - 625/50
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 2
iTerminal 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0010 1x 16 bytes
bInterval 7
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 4
VideoStreaming Interface Descriptor:
bLength 15
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormats 2
wTotalLength 0x038d
bEndPointAddress 130
bmInfo 0
bTerminalLink 3
bStillCaptureMethod 1
bTriggerSupport 1
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 0
bmaControls( 1) 0
VideoStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 6 (FORMAT_MJPEG)
bFormatIndex 1
bNumFrameDescriptors 9
bFlags 1
Fixed-size samples: Yes
bDefaultFrameIndex 1
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 1 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 1
bmCapabilities 0x01
Still image supported
wWidth 1280
wHeight 720
dwMinBitRate 110592000
dwMaxBitRate 663552000
dwMaxVideoFrameBufferSize 2764800
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 2
bmCapabilities 0x01
Still image supported
wWidth 800
wHeight 600
dwMinBitRate 57600000
dwMaxBitRate 345600000
dwMaxVideoFrameBufferSize 1440000
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 3
bmCapabilities 0x01
Still image supported
wWidth 640
wHeight 480
dwMinBitRate 36864000
dwMaxBitRate 221184000
dwMaxVideoFrameBufferSize 921600
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 4
bmCapabilities 0x01
Still image supported
wWidth 640
wHeight 360
dwMinBitRate 27648000
dwMaxBitRate 165888000
dwMaxVideoFrameBufferSize 691200
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 5
bmCapabilities 0x01
Still image supported
wWidth 352
wHeight 288
dwMinBitRate 12165120
dwMaxBitRate 72990720
dwMaxVideoFrameBufferSize 304128
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 6
bmCapabilities 0x01
Still image supported
wWidth 320
wHeight 240
dwMinBitRate 9216000
dwMaxBitRate 55296000
dwMaxVideoFrameBufferSize 230400
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 7
bmCapabilities 0x01
Still image supported
wWidth 176
wHeight 144
dwMinBitRate 3041280
dwMaxBitRate 18247680
dwMaxVideoFrameBufferSize 76032
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 8
bmCapabilities 0x01
Still image supported
wWidth 160
wHeight 120
dwMinBitRate 2304000
dwMaxBitRate 13824000
dwMaxVideoFrameBufferSize 57600
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 9
bmCapabilities 0x01
Still image supported
wWidth 1280
wHeight 720
dwMinBitRate 110592000
dwMaxBitRate 663552000
dwMaxVideoFrameBufferSize 2764800
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 13 (COLORFORMAT)
bColorPrimaries 1 (BT.709,sRGB)
bTransferCharacteristics 1 (BT.709)
bMatrixCoefficients 4 (SMPTE 170M (BT.601))
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED)
bFormatIndex 2
bNumFrameDescriptors 9
guidFormat {32595559-0000-0010-8000-00aa00389b71}
bBitsPerPixel 16
bDefaultFrameIndex 1
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 2 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 34
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 1
bmCapabilities 0x01
Still image supported
wWidth 1280
wHeight 720
dwMinBitRate 73728000
dwMaxBitRate 132710400
dwMaxVideoFrameBufferSize 1843200
dwDefaultFrameInterval 1111111
bFrameIntervalType 2
dwFrameInterval( 0) 1111111
dwFrameInterval( 1) 2000000
VideoStreaming Interface Descriptor:
bLength 38
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 2
bmCapabilities 0x01
Still image supported
wWidth 800
wHeight 600
dwMinBitRate 38400000
dwMaxBitRate 115200000
dwMaxVideoFrameBufferSize 960000
dwDefaultFrameInterval 666666
bFrameIntervalType 3
dwFrameInterval( 0) 666666
dwFrameInterval( 1) 1000000
dwFrameInterval( 2) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 3
bmCapabilities 0x01
Still image supported
wWidth 640
wHeight 480
dwMinBitRate 24576000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 4
bmCapabilities 0x01
Still image supported
wWidth 640
wHeight 360
dwMinBitRate 18432000
dwMaxBitRate 110592000
dwMaxVideoFrameBufferSize 460800
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 5
bmCapabilities 0x01
Still image supported
wWidth 352
wHeight 288
dwMinBitRate 8110080
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 6
bmCapabilities 0x01
Still image supported
wWidth 320
wHeight 240
dwMinBitRate 6144000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 7
bmCapabilities 0x01
Still image supported
wWidth 176
wHeight 144
dwMinBitRate 2027520
dwMaxBitRate 12165120
dwMaxVideoFrameBufferSize 50688
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 400000
dwFrameInterval( 2) 500000
dwFrameInterval( 3) 666666
dwFrameInterval( 4) 1000000
dwFrameInterval( 5) 2000000
VideoStreaming Interface Descriptor:
bLength 38
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 8
bmCapabilities 0x01
Still image supported
wWidth 160
wHeight 120
dwMinBitRate 1536000
dwMaxBitRate 4608000
dwMaxVideoFrameBufferSize 38400
dwDefaultFrameInterval 666666
bFrameIntervalType 3
dwFrameInterval( 0) 666666
dwFrameInterval( 1) 1000000
dwFrameInterval( 2) 2000000
VideoStreaming Interface Descriptor:
bLength 34
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 9
bmCapabilities 0x01
Still image supported
wWidth 1280
wHeight 720
dwMinBitRate 73728000
dwMaxBitRate 132710400
dwMaxVideoFrameBufferSize 1843200
dwDefaultFrameInterval 1111111
bFrameIntervalType 2
dwFrameInterval( 0) 1111111
dwFrameInterval( 1) 2000000
VideoStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 13 (COLORFORMAT)
bColorPrimaries 1 (BT.709,sRGB)
bTransferCharacteristics 1 (BT.709)
bMatrixCoefficients 4 (SMPTE 170M (BT.601))
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 2
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 3
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 4
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 1
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 2
bInterfaceCount 2
bFunctionClass 1 Audio
bFunctionSubClass 0
bFunctionProtocol 0
iFunction 5
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 0
iInterface 5
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 1.00
wTotalLength 0x002b
bInCollection 1
baInterfaceNr(0) 3
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 0
bNrChannels 2
wChannelConfig 0x0003
Left Front (L)
Right Front (R)
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 5
bSourceID 1
bControlSize 2
bmaControls(0) 0x0001
Mute Control
bmaControls(1) 0x0003
Mute Control
Volume Control
bmaControls(2) 0x0003
Mute Control
Volume Control
iFeature 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 5
iTerminal 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 3
bDelay 1 frames
wFormatTag 0x0001 PCM
AudioStreaming Interface Descriptor:
bLength 32
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 8 Discrete
tSamFreq[ 0] 48000
tSamFreq[ 1] 44100
tSamFreq[ 2] 24000
tSamFreq[ 3] 22050
tSamFreq[ 4] 16000
tSamFreq[ 5] 12000
tSamFreq[ 6] 11025
tSamFreq[ 7] 8000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 13
Transfer Type Isochronous
Synch Type Synchronous
Usage Type Data
wMaxPacketSize 0x0064 1x 100 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioStreaming Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 1 Milliseconds
wLockDelay 0x0000
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: Problematic Alt Setting for ALi Corp. Newmine Camera. (plaintext)
2023-10-19 9:15 Problematic Alt Setting for ALi Corp. Newmine Camera. (plaintext) Karel Janda
@ 2023-10-19 22:24 ` Laurent Pinchart
0 siblings, 0 replies; 2+ messages in thread
From: Laurent Pinchart @ 2023-10-19 22:24 UTC (permalink / raw)
To: Karel Janda; +Cc: Linux Media
Hello Karel,
On Thu, Oct 19, 2023 at 11:15:40AM +0200, Karel Janda wrote:
> Hi,
>
> in my class I use ten C-TECH CAM-07HD cameras, detected as
> ID 0402:8841 ALi Corp. Newmine Camera.
> The camera works OK with resolutions <= 320x240@60fps.
> Bigger MJPEG resolutions were laggy, with lots of errors in kern.log:
> usb 1-2: USB isochronous frame lost (-75)
> xhci_hcd 0000:15:00.0: WARN: buffer overrun event for slot 9 ep 4 on endpoint
> Bigger YUY2 resolutions did not get any data. Quirks doesn't help.
> Behavior is the same on (Ubuntu) kernels 6.5.0, 6.2.0, 5.4.0,
> both on 2.0 and 3.0 USB ports.
>
> So I start USB scanning and finally find the reason:
> - camera sends four isochronous interface descriptors for wMaxPacketSize 1024 bytes
> and linux uvcvideo module always chooses bAlternateSetting 4.
> - Windows 10 always chooses bAlternateSetting 1 for the camera
> and bigger resolutions are working OK there.
>
> (I attached listing from lspci -v -d 0402:8841 )
Thank you for the report and the detailed analysis, that's great work !
> This original line of code from drivers/media/usb/uvc/uvc_video.c
> if (psize >= bandwidth && psize <= best_psize) {
>
> chooses last alt setting in case the same wMaxPacketSize values.
>
> If I force using settings 1, 2 or 3 instead in uvc_video.c,
> my REALLY BAD camera starts working OK like a charm, without log errors.
Ouch. A buggy firmware then. That's very common, unfortunately :-(
> So I offer you to change the line above in some future uvc_video.c to:
> if (psize >= bandwidth && psize < best_psize) { //first preferency
>
> which I probe completely solved this problem
> and as Windows does the same will not harm other types of cameras.
Normally I would be fairly worried about making such a change. As I
mentioned, lots of devices are buggy, and picking the first best
alternate setting instead of the last one may well fix the problem for
your device, but break other devices.
In this specific case, however, I have good hopes it would be safe, as
we would implement the same behaviour as Windows 10, and most devices
are tested with Windows (and Windows only, otherwise they would have
caught the firmware bug).
I will submit a patch shortly and CC you.
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-10-19 9:15 Problematic Alt Setting for ALi Corp. Newmine Camera. (plaintext) Karel Janda
2023-10-19 22:24 ` Laurent Pinchart
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