Patch "media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K" has been added to the 5.10-stable tree
Subsystems (3)
A message that is not in the archive (sent off-list or not yet received): [email protected]
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 [email protected] to replace this one?
Quoted 117 lines · On Thu, 2021-07-15 at 16:43 +0200, [email protected] 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=summaryThe 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 <[email protected]> know about it.
From
4c6e0976295add7f0ed94d276c04a3d6f1ea8f83Mon Sep 17 00:00:00 2001
From: Benjamin Drung <[email protected]>
Date: Sat, 5 Jun 2021 22:15:36 +0200
Subject: media: uvcvideo: Fix pixel format change for Elgato Cam Link 4KFrom: Benjamin Drung <[email protected]>
commit
4c6e0976295add7f0ed94d276c04a3d6f1ea8f83upstream.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).
Signed-off-by Benjamin Drung <[email protected]>Signed-off-by Laurent Pinchart <[email protected]>Signed-off-by Mauro Carvalho Chehab <[email protected]>Signed-off-by Greg Kroah-Hartman <[email protected]>--- drivers/media/usb/uvc/uvc_video.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)drivers/media/usb/uvc/uvc_video.c +10
-0@@ -124,10 +124,37 @@ int uvc_query_ctrl(struct uvc_device *destatic 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.
drivers/media/usb/uvc/uvc_video.c int uvc_query_ctrl(struct uvc_device *de · line 150
Quoted 10 lines
drivers/media/usb/uvc/uvc_video.c +10
-0+* 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,
Quoted 15 lines
drivers/media/usb/uvc/uvc_video.c +7
-0+"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; + } +for (i =0 ; i < stream->nformats; ++i) {if (stream->format[i].index == ctrl->bFormatIndex) { format = &stream->format[i];Patches currently in stable-queue which might be from [email protected] are
queue-5.10/media-uvcvideo-fix-pixel-format-change-for-elgato-cam-link-4k.patch
Greg KH
maintainerQuoted 138 lines · Benjamin Drung
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 [email protected] to replace this one?
Quoted 117 lines · On Thu, 2021-07-15 at 16:43 +0200, [email protected] 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=summaryThe 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 <[email protected]> know about it.
From
4c6e0976295add7f0ed94d276c04a3d6f1ea8f83Mon Sep 17 00:00:00 2001
From: Benjamin Drung <[email protected]>
Date: Sat, 5 Jun 2021 22:15:36 +0200
Subject: media: uvcvideo: Fix pixel format change for Elgato Cam Link 4KFrom: Benjamin Drung <[email protected]>
commit
4c6e0976295add7f0ed94d276c04a3d6f1ea8f83upstream.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).
Signed-off-by Benjamin Drung <[email protected]>Signed-off-by Laurent Pinchart <[email protected]>Signed-off-by Mauro Carvalho Chehab <[email protected]>Signed-off-by Greg Kroah-Hartman <[email protected]>--- drivers/media/usb/uvc/uvc_video.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)drivers/media/usb/uvc/uvc_video.c +10
-0@@ -124,10 +124,37 @@ int uvc_query_ctrl(struct uvc_device *destatic 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. drivers/media/usb/uvc/uvc_video.c int uvc_query_ctrl(struct uvc_device *de · line 150
Quoted 10 lines
drivers/media/usb/uvc/uvc_video.c +10
-0+* 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:
Quoted 8 lines
uvc_trace(UVC_TRACE_VIDEO,
drivers/media/usb/uvc/uvc_video.c int uvc_query_ctrl(struct uvc_device *de · line 156
Quoted 6 lines
drivers/media/usb/uvc/uvc_video.c +6
-0+"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
PATCH 1/1 media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
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).
--- drivers/media/usb/uvc/uvc_video.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)
The debug message does't matter much, but I am a perfectionist.
This patch is for kernel <= 5.11.
drivers/media/usb/uvc/uvc_video.c +27 -0
@@ -124,10 +124,37 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,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_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; + } +for (i =0 ; i < stream->nformats; ++i) {if (stream->format[i].index == ctrl->bFormatIndex) { format = &stream->format[i];
Signature · 1 line
2.30.2