Re: [PATCH v6] media: uvcvideo: Fix bandwidth issue for Alcor camera

From: Laurent Pinchart
Date: Thu Apr 10 2025 - 09:19:18 EST

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In reply to: Ricardo Ribalda: "Re: [PATCH v6] media: uvcvideo: Fix bandwidth issue for Alcor camera"
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On Thu, Apr 10, 2025 at 12:02:52PM +0200, Ricardo Ribalda wrote:
> On Thu, 10 Apr 2025 at 11:15, Laurent Pinchart wrote:
> > On Thu, Apr 10, 2025 at 07:32:34AM +0200, Ricardo Ribalda wrote:
> > > On Thu, 10 Apr 2025 at 04:07, Laurent Pinchart wrote:
> > > > On Mon, Mar 24, 2025 at 10:21:20AM +0800, chenchangcheng wrote:
> > > > > From: chenchangcheng <chenchangcheng@xxxxxxxxxx>
> > > > >
> > > > > Some broken device return wrong dwMaxPayloadTransferSize fields,
> > > > > as follows:
> > > > > [ 218.632537] [pid:20427,cpu6,guvcview,8]uvcvideo: Device requested 2752512 B/frame bandwidth.
> > > > > [ 218.632598] [pid:20427,cpu6,guvcview,9]uvcvideo: No fast enough alt setting for requested bandwidth.
> > > > >
> > > > > The maximum packet size of the device is 3 * 1024, according to the
> > > > > logs above, the device needs to apply for a bandwidth of 0x2a0000.
> > > > >
> > > > > Bus 001 Device 008: ID 1b17:6684 Alcor Corp. Slave camera
> > > > > Device Descriptor:
> > > > > bLength 18
> > > > > bDescriptorType 1
> > > > > bcdUSB 2.00
> > > > > bDeviceClass 239 Miscellaneous Device
> > > > > bDeviceSubClass 2
> > > > > bDeviceProtocol 1 Interface Association
> > > > > bMaxPacketSize0 64
> > > > > idVendor 0x1b17
> > > > > idProduct 0x6684
> > > > > bcdDevice 1.05
> > > > > iManufacturer 1 Alcor Corp.
> > > > > iProduct 2 Slave camera
> > > > > iSerial 0
> > > > > bNumConfigurations 1
> > > > > Configuration Descriptor:
> > > > > bLength 9
> > > > > bDescriptorType 2
> > > > > wTotalLength 0x02ad
> > > > > bNumInterfaces 2
> > > > > bConfigurationValue 1
> > > > > iConfiguration 0
> > > > > bmAttributes 0x80
> > > > > (Bus Powered)
> > > > > MaxPower 200mA
> > > > > Interface Association:
> > > > > bLength 8
> > > > > bDescriptorType 11
> > > > > bFirstInterface 0
> > > > > bInterfaceCount 2
> > > > > bFunctionClass 14 Video
> > > > > bFunctionSubClass 3 Video Interface Collection
> > > > > bFunctionProtocol 0
> > > > > iFunction 4 Slave camera
> > > > > Interface Descriptor:
> > > > > bLength 9
> > > > > bDescriptorType 4
> > > > > bInterfaceNumber 0
> > > > > bAlternateSetting 0
> > > > > bNumEndpoints 1
> > > > > bInterfaceClass 14 Video
> > > > > bInterfaceSubClass 1 Video Control
> > > > > bInterfaceProtocol 0
> > > > > iInterface 4 Slave camera
> > > > > VideoControl Interface Descriptor:
> > > > >
> > > > > ....
> > > > >
> > > > > 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 0
> > > > > VideoStreaming Interface Descriptor:
> > > > > bLength 14
> > > > > bDescriptorType 36
> > > > > bDescriptorSubtype 1 (INPUT_HEADER)
> > > > > bNumFormats 1
> > > > > wTotalLength 0x01ef
> > > > > bEndPointAddress 130
> > > > > bmInfo 0
> > > > > bTerminalLink 3
> > > > > bStillCaptureMethod 2
> > > > > bTriggerSupport 1
> > > > > bTriggerUsage 0
> > > > > bControlSize 1
> > > > > bmaControls( 0) 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 0x00
> > > > > Still image unsupported
> > > > > wWidth 1920
> > > > > wHeight 1080
> > > > > dwMinBitRate 248832000
> > > > > dwMaxBitRate 1492992000
> > > > > dwMaxVideoFrameBufferSize 6220800
> > > > > 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 42
> > > > > bDescriptorType 36
> > > > > bDescriptorSubtype 3 (STILL_IMAGE_FRAME)
> > > > > bEndpointAddress 0
> > > > > bNumImageSizePatterns 9
> > > > > wWidth( 0) 1920
> > > > > wHeight( 0) 1080
> > > > > wWidth( 1) 2048
> > > > > wHeight( 1) 1536
> > > > > wWidth( 2) 1280
> > > > > wHeight( 2) 720
> > > > > wWidth( 3) 2592
> > > > > wHeight( 3) 1944
> > > > > wWidth( 4) 1280
> > > > > wHeight( 4) 1024
> > > > > wWidth( 5) 1280
> > > > > wHeight( 5) 960
> > > > > wWidth( 6) 1600
> > > > > wHeight( 6) 1200
> > > > > wWidth( 7) 800
> > > > > wHeight( 7) 600
> > > > > wWidth( 8) 640
> > > > > wHeight( 8) 480
> > > > > bNumCompressionPatterns 0
> > > > > 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 0
> > > > > Endpoint Descriptor:
> > > > > bLength 7
> > > > > bDescriptorType 5
> > > > > bEndpointAddress 0x82 EP 2 IN
> > > > > bmAttributes 5
> > > > > Transfer Type Isochronous
> > > > > Synch Type Asynchronous
> > > > > Usage Type Data
> > > > > wMaxPacketSize 0x1400 3x 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 0
> > > > > Endpoint Descriptor:
> > > > > bLength 7
> > > > > bDescriptorType 5
> > > > > bEndpointAddress 0x82 EP 2 IN
> > > > > bmAttributes 5
> > > > > Transfer Type Isochronous
> > > > > Synch Type Asynchronous
> > > > > Usage Type Data
> > > > > wMaxPacketSize 0x0b84 2x 900 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 0
> > > > > Endpoint Descriptor:
> > > > > bLength 7
> > > > > bDescriptorType 5
> > > > > bEndpointAddress 0x82 EP 2 IN
> > > > > bmAttributes 5
> > > > > Transfer Type Isochronous
> > > > > Synch Type Asynchronous
> > > > > Usage Type Data
> > > > > wMaxPacketSize 0x0c00 2x 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 0
> > > > > Endpoint Descriptor:
> > > > > bLength 7
> > > > > bDescriptorType 5
> > > > > bEndpointAddress 0x82 EP 2 IN
> > > > > bmAttributes 5
> > > > > Transfer Type Isochronous
> > > > > Synch Type Asynchronous
> > > > > Usage Type Data
> > > > > wMaxPacketSize 0x0c00 2x 1024 bytes
> > > > > bInterval 1
> > > > > Device Qualifier (for other device speed):
> > > > > bLength 10
> > > > > bDescriptorType 6
> > > > > bcdUSB 2.00
> > > > > bDeviceClass 239 Miscellaneous Device
> > > > > bDeviceSubClass 2
> > > > > bDeviceProtocol 1 Interface Association
> > > > > bMaxPacketSize0 64
> > > > > bNumConfigurations 1
> > > > > Device Status: 0x0000
> > > > > (Bus Powered)
> > > > >
> > > > > Signed-off-by: chenchangcheng <chenchangcheng@xxxxxxxxxx>
> > > > > ---
> > > > > drivers/media/usb/uvc/uvc_driver.c | 9 +++++++++
> > > > > drivers/media/usb/uvc/uvc_video.c | 10 ++++++++++
> > > > > drivers/media/usb/uvc/uvcvideo.h | 1 +
> > > > > 3 files changed, 20 insertions(+)
> > > > >
> > > > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > > > > index deadbcea5e22..9b1dedf9773b 100644
> > > > > --- a/drivers/media/usb/uvc/uvc_driver.c
> > > > > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > > > > @@ -3023,6 +3023,15 @@ static const struct usb_device_id uvc_ids[] = {
> > > > > .bInterfaceSubClass = 1,
> > > > > .bInterfaceProtocol = 0,
> > > > > .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_STATUS_INTERVAL) },
> > > > > + /* Alcor Corp. Slave camera */
> > > > > + { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> > > > > + | USB_DEVICE_ID_MATCH_INT_INFO,
> > > > > + .idVendor = 0x1b17,
> > > > > + .idProduct = 0x6684,
> > > > > + .bInterfaceClass = USB_CLASS_VIDEO,
> > > > > + .bInterfaceSubClass = 1,
> > > > > + .bInterfaceProtocol = 0,
> > > > > + .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_OVERFLOW_BANDWIDTH) },
> > > > > /* MSI StarCam 370i */
> > > > > { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> > > > > | USB_DEVICE_ID_MATCH_INT_INFO,
> > > > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> > > > > index e3567aeb0007..56f23c363870 100644
> > > > > --- a/drivers/media/usb/uvc/uvc_video.c
> > > > > +++ b/drivers/media/usb/uvc/uvc_video.c
> > > > > @@ -262,6 +262,16 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
> > > > >
> > > > > ctrl->dwMaxPayloadTransferSize = bandwidth;
> > > > > }
> > > > > +
> > > > > + if (stream->intf->num_altsetting > 1 &&
> > > > > + ctrl->dwMaxPayloadTransferSize > stream->maxpsize &&
> > > > > + stream->dev->quirks & UVC_QUIRK_OVERFLOW_BANDWIDTH) {
> > > > > + dev_warn(&stream->intf->dev,
> > > > > + "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
> > > > > + ctrl->dwMaxPayloadTransferSize,
> > > > > + stream->maxpsize);
> > > > > + ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
> > > >
> > > > If the requested bandwidth exceed the maximum the device can use, it's
> > > > clearly a firmware bug. Why do we need a quirk for this, can't we use
> > > > the maximum usable bandwidth in that case, regardless of the particular
> > > > device ?
> > >
> > > Wouldn't that break devices with invalid max_bpi (maxp, maxp_mult,
> > > wBytesPerInterval)?
> >
> > I meant the maximum theoretical bandwidth available to the device,
> > corresponding to the maximum max_bpi value for the current speed. In
> > this case the device is requesting 2752512 B/frame.
>
> I would not count on devices providing different USB descriptors based
> on the current_speed.
> Or if they provide different USB descriptors, they might not have
> tested them properly.
>
> So I would be very careful about not breaking current devices. and the
> quirk is great for that.

I agree about not breaking devices :-)

> But yeah 0x2A0000 is *pretty* big.. USB3 only has 2 bytes for BytesPerInterval
>
> What about?:
>
> #define MAX_BPI_SIXE 0xffff // BytesPerInterval can only hold 2 bytes
> if (stream->intf->num_altsetting > 1 && ctrl->dwMaxPayloadTransferSize
> > MAX_BPI_SIZE) {
> dev_warn_ratelimit(&stream->intf->dev, "UVC non compliance: the max
> payload ....");
> ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
> }

Getting there. Instead of hardcoding a maximum bandwidth, I would just
use stream->maxpsize. The rationale is that a device that requests more
than stream->maxpsize will today generate an error, and streaming won't
be started. Clamping the requests bandwidth to maxpsize will therefore
not break any device, as affected devices are already not working.

> + if (stream->intf->num_altsetting > 1 &&
> + ctrl->dwMaxPayloadTransferSize > stream->maxpsize &&
> + stream->dev->quirks & UVC_QUIRK_OVERFLOW_BANDWIDTH) {
> + dev_warn(&stream->intf->dev,
> + "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
> + ctrl->dwMaxPayloadTransferSize,
> + stream->maxpsize);
> + ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
> + }
>
> > > I think the approach taken by this patch is the most conservative one.
> > > If we get a good number of devices using this quirk we can implement
> > > an heuristic using the info from multiple descriptors.
> > >
> > > > > + }
> > > > > }
> > > > >
> > > > > static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
> > > > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > > > > index 5e388f05f3fc..8b43d725c259 100644
> > > > > --- a/drivers/media/usb/uvc/uvcvideo.h
> > > > > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > > > > @@ -77,6 +77,7 @@
> > > > > #define UVC_QUIRK_DISABLE_AUTOSUSPEND 0x00008000
> > > > > #define UVC_QUIRK_INVALID_DEVICE_SOF 0x00010000
> > > > > #define UVC_QUIRK_MJPEG_NO_EOF 0x00020000
> > > > > +#define UVC_QUIRK_OVERFLOW_BANDWIDTH 0x00040000
> > > > >
> > > > > /* Format flags */
> > > > > #define UVC_FMT_FLAG_COMPRESSED 0x00000001
> > > > >
> > > > > base-commit: 4701f33a10702d5fc577c32434eb62adde0a1ae1

--
Regards,

Laurent Pinchart

Next message: Zijun Hu: "[PATCH 0/2] software node: bug fixes"
Previous message: Oleg Nesterov: "Re: [RFC PATCH] pidfs: ensure consistent ENOENT/ESRCH reporting"
In reply to: Ricardo Ribalda: "Re: [PATCH v6] media: uvcvideo: Fix bandwidth issue for Alcor camera"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]