* [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
@ 2021-04-28 23:03 Benjamin Drung
0 siblings, 0 replies; 7+ messages in thread
From: Benjamin Drung @ 2021-04-28 23:03 UTC (permalink / raw)
To: Laurent Pinchart, Mauro Carvalho Chehab, linux-media, linux-kernel
Cc: Adam Goode, Benjamin Drung, stable
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 add a quirk to correct the malformed data structure.
The quirk 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@vger.kernel.org
Signed-off-by: Benjamin Drung <bdrung@posteo.de>
---
drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
drivers/media/usb/uvc/uvcvideo.h | 1 +
3 files changed, 35 insertions(+)
I am resending this patch since I got no response in the last three
weeks.
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 9a791d8ef200..6ce58950d78b 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -3164,6 +3164,19 @@ static const struct usb_device_id uvc_ids[] = {
.bInterfaceSubClass = 1,
.bInterfaceProtocol = 0,
.driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
+ /*
+ * Elgato Cam Link 4K
+ * Latest firmware as of 2021-03-23 needs this quirk.
+ * MCU: 20.02.19, FPGA: 67
+ */
+ { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
+ | USB_DEVICE_ID_MATCH_INT_INFO,
+ .idVendor = 0x0fd9,
+ .idProduct = 0x0066,
+ .bInterfaceClass = USB_CLASS_VIDEO,
+ .bInterfaceSubClass = 1,
+ .bInterfaceProtocol = 0,
+ .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
/* Generic USB Video Class */
{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index f2f565281e63..06a538d1008b 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -128,6 +128,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
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.
+ */
+ if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
+ __u8 corrected_format_index;
+
+ corrected_format_index = ctrl->bmHint >> 8;
+ uvc_dbg(stream->dev, CONTROL,
+ "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
+ ctrl->bmHint, ctrl->bFormatIndex,
+ ctrl->bFormatIndex, corrected_format_index);
+ ctrl->bmHint = ctrl->bFormatIndex;
+ ctrl->bFormatIndex = corrected_format_index;
+ }
+
for (i = 0; i < stream->nformats; ++i) {
if (stream->format[i].index == ctrl->bFormatIndex) {
format = &stream->format[i];
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 97df5ecd66c9..bf401d5ba27d 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -209,6 +209,7 @@
#define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
#define UVC_QUIRK_FORCE_Y8 0x00000800
#define UVC_QUIRK_FORCE_BPP 0x00001000
+#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
/* Format flags */
#define UVC_FMT_FLAG_COMPRESSED 0x00000001
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
2021-06-05 21:51 ` Laurent Pinchart
@ 2021-06-05 23:10 ` Benjamin Drung
0 siblings, 0 replies; 7+ messages in thread
From: Benjamin Drung @ 2021-06-05 23:10 UTC (permalink / raw)
To: Laurent Pinchart
Cc: Linus Torvalds, Adam Goode, Mauro Carvalho Chehab, linux-media,
linux-kernel, stable
Am Sonntag, den 06.06.2021, 00:51 +0300 schrieb Laurent Pinchart:
> Hi Benjamin,
>
> On Sat, Jun 05, 2021 at 08:19:56AM +0000, Benjamin Drung wrote:
> > Am Samstag, den 05.06.2021, 01:21 +0300 schrieb Laurent Pinchart:
> > > On Fri, Jun 04, 2021 at 05:19:42PM +0000, Benjamin Drung wrote:
> > > > 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.
> > >
> > > *sigh* :-( Same vendors are depressingly unable to perform even the most
> > > basic conformance testing.
> > >
> > > Thanks for all this analysis and bug reports.
> > >
> > > > Therefore add a quirk to correct the malformed data structure.
> > > >
> > > > The quirk 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@vger.kernel.org
> > > > Signed-off-by: Benjamin Drung <bdrung@posteo.de>
> > > > ---
> > > >
> > > > I am sending this patch a fourth time since I got no response and the
> > > > last resend is over a month ago. This time I am including Linus Torvalds
> > > > in the hope to get it reviewed.
> > >
> > > The resend got to the top of my mailbox and I had time to review it
> > > before it got burried again. Thanks for not giving up.
> >
> > Thanks for reviewing the patch.
>
> I'll try not to be that late for v3/v4 :-)
Thanks. :)
> > > > drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
> > > > drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
> > > > drivers/media/usb/uvc/uvcvideo.h | 1 +
> > > > 3 files changed, 35 insertions(+)
> > > >
> > > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > > > index 9a791d8ef200..6ce58950d78b 100644
> > > > --- a/drivers/media/usb/uvc/uvc_driver.c
> > > > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > > > @@ -3164,6 +3164,19 @@ static const struct usb_device_id uvc_ids[] = {
> > > > .bInterfaceSubClass = 1,
> > > > .bInterfaceProtocol = 0,
> > > > .driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
> > > > + /*
> > > > + * Elgato Cam Link 4K
> > > > + * Latest firmware as of 2021-03-23 needs this quirk.
> > > > + * MCU: 20.02.19, FPGA: 67
> > > > + */
> > > > + { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> > > > + | USB_DEVICE_ID_MATCH_INT_INFO,
> > > > + .idVendor = 0x0fd9,
> > > > + .idProduct = 0x0066,
> > > > + .bInterfaceClass = USB_CLASS_VIDEO,
> > > > + .bInterfaceSubClass = 1,
> > > > + .bInterfaceProtocol = 0,
> > > > + .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
> > > > /* Generic USB Video Class */
> > > > { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
> > > > { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
> > > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> > > > index a777b389a66e..910d22233d74 100644
> > > > --- a/drivers/media/usb/uvc/uvc_video.c
> > > > +++ b/drivers/media/usb/uvc/uvc_video.c
> > > > @@ -131,6 +131,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
> > > > 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.
> > > > + */
> > > > + if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
> > >
> > > Given that this is likely not going to affect other devices (at least in
> > > the same way), I'd rather test the USB VID:PID that add a quirk.
> > > Something along the lines of
> > >
> > > if (usb_match_one_id(stream->dev->intf, USB_DEVICE(0x0fd9, 0x0066)) {
> >
> > Adam Goode suggested that the Game Capture HD 60 S+ (0fd9:006a) from the
> > same vendor is probably affected by the same bug. I cannot test this
> > assumption since I don't have this device (I am open for a loaner
> > device). An Internet search did not reveal bug reports in this regard.
> > Most search results referred to older versions (e.g. without + or
> > without S+) Do you still prefer to test the USB VID:PID?
>
> What bothers me a bit with a quirk is that it's supposed to be a generic
> mechanism for bugs that affect a wide variety of devices. We could have
> a small array of device match entries as in uvc_ctrl_prune_entity() if
> you don't expect more than a handful of devices to be affected.
> Otherwise, if you think a quirk is better, let's go for that, but let's
> then name it with the vendor name (UVC_QUIRK_ELGATE_VIDEO_CONTROL or
> similar).
I expect that at most a handful devices might need that special
handling. Only a few companies produce video grabbers that support 4K.
All the cheap ones only support FullHD. So I don't expect that the chip
and firmware in the Cam Link is used in many other devices.
I had a look at the device array in uvc_ctrl_prune_entity(). Since that
mechanism is used there and in other places, I am fine with using it.
You have probably more experience what do implement as quirk and what to
cover with if conditions. So let's follow your suggestion and in case we
find more affected devices, we can still change it to a quirk.
> > > > + __u8 corrected_format_index;
> > > > +
> > > > + corrected_format_index = ctrl->bmHint >> 8;
> > > > + uvc_dbg(stream->dev, CONTROL,
> > > > + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
> > > > + ctrl->bmHint, ctrl->bFormatIndex,
> > > > + ctrl->bFormatIndex, corrected_format_index);
> > > > + ctrl->bmHint = ctrl->bFormatIndex;
> > >
> > > According to your description above, this will always be 1. Is the third
> > > byte always 1 because the driver always sets bmHint to 1, or would it
> > > have a different value if we set bmHint to something else ? In the first
> > > case I'd hardcode ctrl->bmHint to 1 here.
> >
> > I will test setting bmHint to something else than 1 to check. I will
> > report back then. Either follow your sugstion or update the comment.
>
> Thanks.
>
> > > > + ctrl->bFormatIndex = corrected_format_index;
> > > > + }
> > > > +
> > > > for (i = 0; i < stream->nformats; ++i) {
> > > > if (stream->format[i].index == ctrl->bFormatIndex) {
> > > > format = &stream->format[i];
> > > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > > > index cce5e38133cd..cbb4ef61a64d 100644
> > > > --- a/drivers/media/usb/uvc/uvcvideo.h
> > > > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > > > @@ -209,6 +209,7 @@
> > > > #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
> > > > #define UVC_QUIRK_FORCE_Y8 0x00000800
> > > > #define UVC_QUIRK_FORCE_BPP 0x00001000
> > > > +#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
> > > >
> > > >
> > > > /* Format flags */
> > > > #define UVC_FMT_FLAG_COMPRESSED 0x00000001
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
2021-06-05 8:19 ` Benjamin Drung
@ 2021-06-05 21:51 ` Laurent Pinchart
2021-06-05 23:10 ` Benjamin Drung
0 siblings, 1 reply; 7+ messages in thread
From: Laurent Pinchart @ 2021-06-05 21:51 UTC (permalink / raw)
To: Benjamin Drung
Cc: Linus Torvalds, Adam Goode, Mauro Carvalho Chehab, linux-media,
linux-kernel, stable
Hi Benjamin,
On Sat, Jun 05, 2021 at 08:19:56AM +0000, Benjamin Drung wrote:
> Am Samstag, den 05.06.2021, 01:21 +0300 schrieb Laurent Pinchart:
> > On Fri, Jun 04, 2021 at 05:19:42PM +0000, Benjamin Drung wrote:
> > > 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.
> >
> > *sigh* :-( Same vendors are depressingly unable to perform even the most
> > basic conformance testing.
> >
> > Thanks for all this analysis and bug reports.
> >
> > > Therefore add a quirk to correct the malformed data structure.
> > >
> > > The quirk 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@vger.kernel.org
> > > Signed-off-by: Benjamin Drung <bdrung@posteo.de>
> > > ---
> > >
> > > I am sending this patch a fourth time since I got no response and the
> > > last resend is over a month ago. This time I am including Linus Torvalds
> > > in the hope to get it reviewed.
> >
> > The resend got to the top of my mailbox and I had time to review it
> > before it got burried again. Thanks for not giving up.
>
> Thanks for reviewing the patch.
I'll try not to be that late for v3/v4 :-)
> > > drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
> > > drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
> > > drivers/media/usb/uvc/uvcvideo.h | 1 +
> > > 3 files changed, 35 insertions(+)
> > >
> > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > > index 9a791d8ef200..6ce58950d78b 100644
> > > --- a/drivers/media/usb/uvc/uvc_driver.c
> > > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > > @@ -3164,6 +3164,19 @@ static const struct usb_device_id uvc_ids[] = {
> > > .bInterfaceSubClass = 1,
> > > .bInterfaceProtocol = 0,
> > > .driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
> > > + /*
> > > + * Elgato Cam Link 4K
> > > + * Latest firmware as of 2021-03-23 needs this quirk.
> > > + * MCU: 20.02.19, FPGA: 67
> > > + */
> > > + { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> > > + | USB_DEVICE_ID_MATCH_INT_INFO,
> > > + .idVendor = 0x0fd9,
> > > + .idProduct = 0x0066,
> > > + .bInterfaceClass = USB_CLASS_VIDEO,
> > > + .bInterfaceSubClass = 1,
> > > + .bInterfaceProtocol = 0,
> > > + .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
> > > /* Generic USB Video Class */
> > > { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
> > > { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
> > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> > > index a777b389a66e..910d22233d74 100644
> > > --- a/drivers/media/usb/uvc/uvc_video.c
> > > +++ b/drivers/media/usb/uvc/uvc_video.c
> > > @@ -131,6 +131,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
> > > 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.
> > > + */
> > > + if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
> >
> > Given that this is likely not going to affect other devices (at least in
> > the same way), I'd rather test the USB VID:PID that add a quirk.
> > Something along the lines of
> >
> > if (usb_match_one_id(stream->dev->intf, USB_DEVICE(0x0fd9, 0x0066)) {
>
> Adam Goode suggested that the Game Capture HD 60 S+ (0fd9:006a) from the
> same vendor is probably affected by the same bug. I cannot test this
> assumption since I don't have this device (I am open for a loaner
> device). An Internet search did not reveal bug reports in this regard.
> Most search results referred to older versions (e.g. without + or
> without S+) Do you still prefer to test the USB VID:PID?
What bothers me a bit with a quirk is that it's supposed to be a generic
mechanism for bugs that affect a wide variety of devices. We could have
a small array of device match entries as in uvc_ctrl_prune_entity() if
you don't expect more than a handful of devices to be affected.
Otherwise, if you think a quirk is better, let's go for that, but let's
then name it with the vendor name (UVC_QUIRK_ELGATE_VIDEO_CONTROL or
similar).
> > > + __u8 corrected_format_index;
> > > +
> > > + corrected_format_index = ctrl->bmHint >> 8;
> > > + uvc_dbg(stream->dev, CONTROL,
> > > + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
> > > + ctrl->bmHint, ctrl->bFormatIndex,
> > > + ctrl->bFormatIndex, corrected_format_index);
> > > + ctrl->bmHint = ctrl->bFormatIndex;
> >
> > According to your description above, this will always be 1. Is the third
> > byte always 1 because the driver always sets bmHint to 1, or would it
> > have a different value if we set bmHint to something else ? In the first
> > case I'd hardcode ctrl->bmHint to 1 here.
>
> I will test setting bmHint to something else than 1 to check. I will
> report back then. Either follow your sugstion or update the comment.
Thanks.
> > > + ctrl->bFormatIndex = corrected_format_index;
> > > + }
> > > +
> > > for (i = 0; i < stream->nformats; ++i) {
> > > if (stream->format[i].index == ctrl->bFormatIndex) {
> > > format = &stream->format[i];
> > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > > index cce5e38133cd..cbb4ef61a64d 100644
> > > --- a/drivers/media/usb/uvc/uvcvideo.h
> > > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > > @@ -209,6 +209,7 @@
> > > #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
> > > #define UVC_QUIRK_FORCE_Y8 0x00000800
> > > #define UVC_QUIRK_FORCE_BPP 0x00001000
> > > +#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
> > >
> > > /* Format flags */
> > > #define UVC_FMT_FLAG_COMPRESSED 0x00000001
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
2021-06-04 22:21 ` Laurent Pinchart
@ 2021-06-05 8:19 ` Benjamin Drung
2021-06-05 21:51 ` Laurent Pinchart
0 siblings, 1 reply; 7+ messages in thread
From: Benjamin Drung @ 2021-06-05 8:19 UTC (permalink / raw)
To: Laurent Pinchart
Cc: Linus Torvalds, Adam Goode, Mauro Carvalho Chehab, linux-media,
linux-kernel, stable
Hi Laurent,
Am Samstag, den 05.06.2021, 01:21 +0300 schrieb Laurent Pinchart:
> Hi Benjamin,
>
> Thank you for the patch.
>
> On Fri, Jun 04, 2021 at 05:19:42PM +0000, Benjamin Drung wrote:
> > 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.
>
> *sigh* :-( Same vendors are depressingly unable to perform even the most
> basic conformance testing.
>
> Thanks for all this analysis and bug reports.
>
> > Therefore add a quirk to correct the malformed data structure.
> >
> > The quirk 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@vger.kernel.org
> > Signed-off-by: Benjamin Drung <bdrung@posteo.de>
> > ---
> >
> > I am sending this patch a fourth time since I got no response and the
> > last resend is over a month ago. This time I am including Linus Torvalds
> > in the hope to get it reviewed.
>
> The resend got to the top of my mailbox and I had time to review it
> before it got burried again. Thanks for not giving up.
Thanks for reviewing the patch.
> > drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
> > drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
> > drivers/media/usb/uvc/uvcvideo.h | 1 +
> > 3 files changed, 35 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index 9a791d8ef200..6ce58950d78b 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -3164,6 +3164,19 @@ static const struct usb_device_id uvc_ids[] = {
> > .bInterfaceSubClass = 1,
> > .bInterfaceProtocol = 0,
> > .driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
> > + /*
> > + * Elgato Cam Link 4K
> > + * Latest firmware as of 2021-03-23 needs this quirk.
> > + * MCU: 20.02.19, FPGA: 67
> > + */
> > + { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> > + | USB_DEVICE_ID_MATCH_INT_INFO,
> > + .idVendor = 0x0fd9,
> > + .idProduct = 0x0066,
> > + .bInterfaceClass = USB_CLASS_VIDEO,
> > + .bInterfaceSubClass = 1,
> > + .bInterfaceProtocol = 0,
> > + .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
> > /* Generic USB Video Class */
> > { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
> > { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
> > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> > index a777b389a66e..910d22233d74 100644
> > --- a/drivers/media/usb/uvc/uvc_video.c
> > +++ b/drivers/media/usb/uvc/uvc_video.c
> > @@ -131,6 +131,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
> > 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.
> > + */
> > + if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
>
> Given that this is likely not going to affect other devices (at least in
> the same way), I'd rather test the USB VID:PID that add a quirk.
> Something along the lines of
>
> if (usb_match_one_id(stream->dev->intf, USB_DEVICE(0x0fd9, 0x0066)) {
Adam Goode suggested that the Game Capture HD 60 S+ (0fd9:006a) from the
same vendor is probably affected by the same bug. I cannot test this
assumption since I don't have this device (I am open for a loaner
device). An Internet search did not reveal bug reports in this regard.
Most search results referred to older versions (e.g. without + or
without S+) Do you still prefer to test the USB VID:PID?
> > + __u8 corrected_format_index;
> > +
> > + corrected_format_index = ctrl->bmHint >> 8;
> > + uvc_dbg(stream->dev, CONTROL,
> > + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
> > + ctrl->bmHint, ctrl->bFormatIndex,
> > + ctrl->bFormatIndex, corrected_format_index);
> > + ctrl->bmHint = ctrl->bFormatIndex;
>
> According to your description above, this will always be 1. Is the third
> byte always 1 because the driver always sets bmHint to 1, or would it
> have a different value if we set bmHint to something else ? In the first
> case I'd hardcode ctrl->bmHint to 1 here.
I will test setting bmHint to something else than 1 to check. I will
report back then. Either follow your sugstion or update the comment.
> > + ctrl->bFormatIndex = corrected_format_index;
> > + }
> > +
> > for (i = 0; i < stream->nformats; ++i) {
> > if (stream->format[i].index == ctrl->bFormatIndex) {
> > format = &stream->format[i];
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index cce5e38133cd..cbb4ef61a64d 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -209,6 +209,7 @@
> > #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
> > #define UVC_QUIRK_FORCE_Y8 0x00000800
> > #define UVC_QUIRK_FORCE_BPP 0x00001000
> > +#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
> >
> >
> > /* Format flags */
> > #define UVC_FMT_FLAG_COMPRESSED 0x00000001
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
2021-06-04 17:19 ` Benjamin Drung
@ 2021-06-04 22:21 ` Laurent Pinchart
2021-06-05 8:19 ` Benjamin Drung
0 siblings, 1 reply; 7+ messages in thread
From: Laurent Pinchart @ 2021-06-04 22:21 UTC (permalink / raw)
To: Benjamin Drung
Cc: Linus Torvalds, Adam Goode, Mauro Carvalho Chehab, linux-media,
linux-kernel, stable
Hi Benjamin,
Thank you for the patch.
On Fri, Jun 04, 2021 at 05:19:42PM +0000, Benjamin Drung wrote:
> 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.
*sigh* :-( Same vendors are depressingly unable to perform even the most
basic conformance testing.
Thanks for all this analysis and bug reports.
> Therefore add a quirk to correct the malformed data structure.
>
> The quirk 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@vger.kernel.org
> Signed-off-by: Benjamin Drung <bdrung@posteo.de>
> ---
>
> I am sending this patch a fourth time since I got no response and the
> last resend is over a month ago. This time I am including Linus Torvalds
> in the hope to get it reviewed.
The resend got to the top of my mailbox and I had time to review it
before it got burried again. Thanks for not giving up.
> drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
> drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
> drivers/media/usb/uvc/uvcvideo.h | 1 +
> 3 files changed, 35 insertions(+)
>
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 9a791d8ef200..6ce58950d78b 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -3164,6 +3164,19 @@ static const struct usb_device_id uvc_ids[] = {
> .bInterfaceSubClass = 1,
> .bInterfaceProtocol = 0,
> .driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
> + /*
> + * Elgato Cam Link 4K
> + * Latest firmware as of 2021-03-23 needs this quirk.
> + * MCU: 20.02.19, FPGA: 67
> + */
> + { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> + | USB_DEVICE_ID_MATCH_INT_INFO,
> + .idVendor = 0x0fd9,
> + .idProduct = 0x0066,
> + .bInterfaceClass = USB_CLASS_VIDEO,
> + .bInterfaceSubClass = 1,
> + .bInterfaceProtocol = 0,
> + .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
> /* Generic USB Video Class */
> { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
> { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index a777b389a66e..910d22233d74 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -131,6 +131,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
> 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.
> + */
> + if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
Given that this is likely not going to affect other devices (at least in
the same way), I'd rather test the USB VID:PID that add a quirk.
Something along the lines of
if (usb_match_one_id(stream->dev->intf, USB_DEVICE(0x0fd9, 0x0066)) {
> + __u8 corrected_format_index;
> +
> + corrected_format_index = ctrl->bmHint >> 8;
> + uvc_dbg(stream->dev, CONTROL,
> + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
> + ctrl->bmHint, ctrl->bFormatIndex,
> + ctrl->bFormatIndex, corrected_format_index);
> + ctrl->bmHint = ctrl->bFormatIndex;
According to your description above, this will always be 1. Is the third
byte always 1 because the driver always sets bmHint to 1, or would it
have a different value if we set bmHint to something else ? In the first
case I'd hardcode ctrl->bmHint to 1 here.
> + ctrl->bFormatIndex = corrected_format_index;
> + }
> +
> for (i = 0; i < stream->nformats; ++i) {
> if (stream->format[i].index == ctrl->bFormatIndex) {
> format = &stream->format[i];
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index cce5e38133cd..cbb4ef61a64d 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -209,6 +209,7 @@
> #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
> #define UVC_QUIRK_FORCE_Y8 0x00000800
> #define UVC_QUIRK_FORCE_BPP 0x00001000
> +#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
>
> /* Format flags */
> #define UVC_FMT_FLAG_COMPRESSED 0x00000001
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
2020-11-23 15:02 PROBLEM: Broken pixel format " Adam Goode
2021-04-06 18:52 ` [PATCH v2] media: uvcvideo: Fix pixel format change " Benjamin Drung
@ 2021-06-04 17:19 ` Benjamin Drung
2021-06-04 22:21 ` Laurent Pinchart
1 sibling, 1 reply; 7+ messages in thread
From: Benjamin Drung @ 2021-06-04 17:19 UTC (permalink / raw)
To: Linus Torvalds, Adam Goode, Laurent Pinchart, Mauro Carvalho Chehab
Cc: linux-media, linux-kernel, Benjamin Drung, stable
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 add a quirk to correct the malformed data structure.
The quirk 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@vger.kernel.org
Signed-off-by: Benjamin Drung <bdrung@posteo.de>
---
I am sending this patch a fourth time since I got no response and the
last resend is over a month ago. This time I am including Linus Torvalds
in the hope to get it reviewed.
drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
drivers/media/usb/uvc/uvcvideo.h | 1 +
3 files changed, 35 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 9a791d8ef200..6ce58950d78b 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -3164,6 +3164,19 @@ static const struct usb_device_id uvc_ids[] = {
.bInterfaceSubClass = 1,
.bInterfaceProtocol = 0,
.driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
+ /*
+ * Elgato Cam Link 4K
+ * Latest firmware as of 2021-03-23 needs this quirk.
+ * MCU: 20.02.19, FPGA: 67
+ */
+ { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
+ | USB_DEVICE_ID_MATCH_INT_INFO,
+ .idVendor = 0x0fd9,
+ .idProduct = 0x0066,
+ .bInterfaceClass = USB_CLASS_VIDEO,
+ .bInterfaceSubClass = 1,
+ .bInterfaceProtocol = 0,
+ .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
/* Generic USB Video Class */
{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index a777b389a66e..910d22233d74 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -131,6 +131,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
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.
+ */
+ if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
+ __u8 corrected_format_index;
+
+ corrected_format_index = ctrl->bmHint >> 8;
+ uvc_dbg(stream->dev, CONTROL,
+ "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
+ ctrl->bmHint, ctrl->bFormatIndex,
+ ctrl->bFormatIndex, corrected_format_index);
+ ctrl->bmHint = ctrl->bFormatIndex;
+ ctrl->bFormatIndex = corrected_format_index;
+ }
+
for (i = 0; i < stream->nformats; ++i) {
if (stream->format[i].index == ctrl->bFormatIndex) {
format = &stream->format[i];
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index cce5e38133cd..cbb4ef61a64d 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -209,6 +209,7 @@
#define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
#define UVC_QUIRK_FORCE_Y8 0x00000800
#define UVC_QUIRK_FORCE_BPP 0x00001000
+#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
/* Format flags */
#define UVC_FMT_FLAG_COMPRESSED 0x00000001
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K
2020-11-23 15:02 PROBLEM: Broken pixel format " Adam Goode
@ 2021-04-06 18:52 ` Benjamin Drung
2021-06-04 17:19 ` Benjamin Drung
1 sibling, 0 replies; 7+ messages in thread
From: Benjamin Drung @ 2021-04-06 18:52 UTC (permalink / raw)
To: Adam Goode, Laurent Pinchart, Mauro Carvalho Chehab
Cc: linux-media, linux-kernel, Benjamin Drung, stable
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 add a quirk to correct the malformed data structure.
The quirk 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@vger.kernel.org
Signed-off-by: Benjamin Drung <bdrung@posteo.de>
---
In version 2, I only enhanced the comment in the code to document that
the quirk is only applied to broken responses (guarded by
ctrl->bmHint > 255). So in case Elgato fixes the firmware, the quirk
will be skipped.
Adam Goode suggested to also apply the quirk to Elgato Game Capture HD
60 S+ (0fd9:006a). Can someone owning this device test this patch/quirk
(or can someone borrow me one for testing)?
Feel free to propose a better name for the quirk than
UVC_QUIRK_FIX_FORMAT_INDEX.
To backport to version 5.11 and earlier, the line
```
uvc_dbg(stream->dev, CONTROL,
```
needs to be changed back to
```
uvc_trace(UVC_TRACE_CONTROL,
```
drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++++++
drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++
drivers/media/usb/uvc/uvcvideo.h | 1 +
3 files changed, 35 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 30ef2a3110f7..4f245b3f8bd9 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -3132,6 +3132,19 @@ static const struct usb_device_id uvc_ids[] = {
.bInterfaceSubClass = 1,
.bInterfaceProtocol = 0,
.driver_info = UVC_INFO_META(V4L2_META_FMT_D4XX) },
+ /*
+ * Elgato Cam Link 4K
+ * Latest firmware as of 2021-03-23 needs this quirk.
+ * MCU: 20.02.19, FPGA: 67
+ */
+ { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
+ | USB_DEVICE_ID_MATCH_INT_INFO,
+ .idVendor = 0x0fd9,
+ .idProduct = 0x0066,
+ .bInterfaceClass = USB_CLASS_VIDEO,
+ .bInterfaceSubClass = 1,
+ .bInterfaceProtocol = 0,
+ .driver_info = UVC_INFO_QUIRK(UVC_QUIRK_FIX_FORMAT_INDEX) },
/* Generic USB Video Class */
{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index f2f565281e63..06a538d1008b 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -128,6 +128,27 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
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.
+ */
+ if (stream->dev->quirks & UVC_QUIRK_FIX_FORMAT_INDEX && ctrl->bmHint > 255) {
+ __u8 corrected_format_index;
+
+ corrected_format_index = ctrl->bmHint >> 8;
+ uvc_dbg(stream->dev, CONTROL,
+ "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\n",
+ ctrl->bmHint, ctrl->bFormatIndex,
+ ctrl->bFormatIndex, corrected_format_index);
+ ctrl->bmHint = ctrl->bFormatIndex;
+ ctrl->bFormatIndex = corrected_format_index;
+ }
+
for (i = 0; i < stream->nformats; ++i) {
if (stream->format[i].index == ctrl->bFormatIndex) {
format = &stream->format[i];
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 97df5ecd66c9..bf401d5ba27d 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -209,6 +209,7 @@
#define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
#define UVC_QUIRK_FORCE_Y8 0x00000800
#define UVC_QUIRK_FORCE_BPP 0x00001000
+#define UVC_QUIRK_FIX_FORMAT_INDEX 0x00002000
/* Format flags */
#define UVC_FMT_FLAG_COMPRESSED 0x00000001
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-06-05 23:10 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-28 23:03 [PATCH v2] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K Benjamin Drung
-- strict thread matches above, loose matches on Subject: below --
2020-11-23 15:02 PROBLEM: Broken pixel format " Adam Goode
2021-04-06 18:52 ` [PATCH v2] media: uvcvideo: Fix pixel format change " Benjamin Drung
2021-06-04 17:19 ` Benjamin Drung
2021-06-04 22:21 ` Laurent Pinchart
2021-06-05 8:19 ` Benjamin Drung
2021-06-05 21:51 ` Laurent Pinchart
2021-06-05 23:10 ` Benjamin Drung
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