On Thu, Jul 15, 2021 at 06:00:10PM +0000, Benjamin Drung wrote: > Hi Greg, > > thanks for applying/staging the commit for the stable release. For > kernel <= 5.11 the patch needs a small modification for the debug log. > See below. Should I send an adapted patch to stable@xxxxxxxxxxxxxxx to > replace this one? > > On Thu, 2021-07-15 at 16:43 +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > This is a note to let you know that I've just added the patch titled > > > > media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K > > > > to the 5.10-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > The filename of the patch is: > > media-uvcvideo-fix-pixel-format-change-for-elgato-cam-link-4k.patch > > and it can be found in the queue-5.10 subdirectory. > > > > If you, or anyone else, feels it should not be added to the stable tree, > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > > > From 4c6e0976295add7f0ed94d276c04a3d6f1ea8f83 Mon Sep 17 00:00:00 2001 > > From: Benjamin Drung <bdrung@xxxxxxxxx> > > Date: Sat, 5 Jun 2021 22:15:36 +0200 > > Subject: media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K > > > > From: Benjamin Drung <bdrung@xxxxxxxxx> > > > > commit 4c6e0976295add7f0ed94d276c04a3d6f1ea8f83 upstream. > > > > The Elgato Cam Link 4K HDMI video capture card reports to support three > > different pixel formats, where the first format depends on the connected > > HDMI device. > > > > ``` > > $ v4l2-ctl -d /dev/video0 --list-formats-ext > > ioctl: VIDIOC_ENUM_FMT > > Type: Video Capture > > > > [0]: 'NV12' (Y/CbCr 4:2:0) > > Size: Discrete 3840x2160 > > Interval: Discrete 0.033s (29.970 fps) > > [1]: 'NV12' (Y/CbCr 4:2:0) > > Size: Discrete 3840x2160 > > Interval: Discrete 0.033s (29.970 fps) > > [2]: 'YU12' (Planar YUV 4:2:0) > > Size: Discrete 3840x2160 > > Interval: Discrete 0.033s (29.970 fps) > > ``` > > > > Changing the pixel format to anything besides the first pixel format > > does not work: > > > > ``` > > $ v4l2-ctl -d /dev/video0 --try-fmt-video pixelformat=YU12 > > Format Video Capture: > > Width/Height : 3840/2160 > > Pixel Format : 'NV12' (Y/CbCr 4:2:0) > > Field : None > > Bytes per Line : 3840 > > Size Image : 12441600 > > Colorspace : sRGB > > Transfer Function : Rec. 709 > > YCbCr/HSV Encoding: Rec. 709 > > Quantization : Default (maps to Limited Range) > > Flags : > > ``` > > > > User space applications like VLC might show an error message on the > > terminal in that case: > > > > ``` > > libv4l2: error set_fmt gave us a different result than try_fmt! > > ``` > > > > Depending on the error handling of the user space applications, they > > might display a distorted video, because they use the wrong pixel format > > for decoding the stream. > > > > The Elgato Cam Link 4K responds to the USB video probe > > VS_PROBE_CONTROL/VS_COMMIT_CONTROL with a malformed data structure: The > > second byte contains bFormatIndex (instead of being the second byte of > > bmHint). The first byte is always zero. The third byte is always 1. > > > > The firmware bug was reported to Elgato on 2020-12-01 and it was > > forwarded by the support team to the developers as feature request. > > There is no firmware update available since then. The latest firmware > > for Elgato Cam Link 4K as of 2021-03-23 has MCU 20.02.19 and FPGA 67. > > > > Therefore correct the malformed data structure for this device. The > > change was successfully tested with VLC, OBS, and Chromium using > > different pixel formats (YUYV, NV12, YU12), resolutions (3840x2160, > > 1920x1080), and frame rates (29.970 and 59.940 fps). > > > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Benjamin Drung <bdrung@xxxxxxxxx> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > --- > > drivers/media/usb/uvc/uvc_video.c | 27 +++++++++++++++++++++++++++ > > 1 file changed, 27 insertions(+) > > > > --- a/drivers/media/usb/uvc/uvc_video.c > > +++ b/drivers/media/usb/uvc/uvc_video.c > > @@ -124,10 +124,37 @@ int uvc_query_ctrl(struct uvc_device *de > > static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, > > struct uvc_streaming_control *ctrl) > > { > > + static const struct usb_device_id elgato_cam_link_4k = { > > + USB_DEVICE(0x0fd9, 0x0066) > > + }; > > struct uvc_format *format = NULL; > > struct uvc_frame *frame = NULL; > > unsigned int i; > > > > + /* > > + * The response of the Elgato Cam Link 4K is incorrect: The second byte > > + * contains bFormatIndex (instead of being the second byte of bmHint). > > + * The first byte is always zero. The third byte is always 1. > > + * > > + * The UVC 1.5 class specification defines the first five bits in the > > + * bmHint bitfield. The remaining bits are reserved and should be zero. > > + * Therefore a valid bmHint will be less than 32. > > + * > > + * Latest Elgato Cam Link 4K firmware as of 2021-03-23 needs this fix. > > + * MCU: 20.02.19, FPGA: 67 > > + */ > > + if (usb_match_one_id(stream->dev->intf, &elgato_cam_link_4k) && > > + ctrl->bmHint > 255) { > > + u8 corrected_format_index = ctrl->bmHint >> 8; > > + > > + /* uvc_dbg(stream->dev, VIDEO, > > Instead of commenting out the debug log, this line needs to be replaced by: > > uvc_trace(UVC_TRACE_VIDEO, > > > + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: %u} to {bmHint: 0x%04x, bFormatIndex: %u}\n", > > + ctrl->bmHint, ctrl->bFormatIndex, > > + 1, corrected_format_index); */ > > + ctrl->bmHint = 1; > > + ctrl->bFormatIndex = corrected_format_index; > > + } Yes, can you send an updated version? But does it really matter? thanks, greg k-h
