github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 17:47:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

media: uvcvideo: Fix sequence number when no EOF

Browse Source 
If the driver could not detect the EOF, the sequence number is increased
twice:
 1) When we enter uvc_video_decode_start() with the old buffer and FID has
   flipped => We return -EAGAIN and last_fid is not flipped
 2) When we enter uvc_video_decode_start() with the new buffer.

Fix this issue by moving the new frame detection logic earlier in
uvc_video_decode_start().

This also has some nice side affects:

- The error status from the new packet will no longer get propagated
  to the previous frame-buffer.
- uvc_video_clock_decode() will no longer update the previous frame
  buf->stf with info from the new packet.
- uvc_video_clock_decode() and uvc_video_stats_decode() will no longer
  get called twice for the same packet.

Cc: stable@kernel.org
Fixes: 650b95feee ("[media] uvcvideo: Generate discontinuous sequence numbers when frames are lost")
Reported-by: Hans de Goede <hansg@kernel.org>
Closes: https://lore.kernel.org/linux-media/CANiDSCuj4cPuB5_v2xyvAagA5FjoN8V5scXiFFOeD3aKDMqkCg@mail.gmail.com/T/#me39fb134e8c2c085567a31548c3403eb639625e4
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Ricardo Ribalda 2026-03-23 09:53:52 +00:00 committed by Hans Verkuil
parent bc1ba628e3
commit f078966ca1
1 changed files with 47 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

92
drivers/media/usb/uvc/uvc_video.c
View File

@ -1168,6 +1168,53 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
header_len = data[0];
fid = data[1] & UVC_STREAM_FID;
/*
* Mark the buffer as done if we're at the beginning of a new frame.
* End of frame detection is better implemented by checking the EOF
* bit (FID bit toggling is delayed by one frame compared to the EOF
* bit), but some devices don't set the bit at end of frame (and the
* last payload can be lost anyway). We thus must check if the FID has
* been toggled.
*
* stream->last_fid is initialized to -1, and buf->bytesused to 0,
* so the first isochronous frame will never trigger an end of frame
* detection.
*
* Empty buffers (bytesused == 0) don't trigger end of frame detection
* as it doesn't make sense to return an empty buffer. This also
* avoids detecting end of frame conditions at FID toggling if the
* previous payload had the EOF bit set.
*/
if (fid != stream->last_fid && buf && buf->bytesused != 0) {
uvc_dbg(stream->dev, FRAME,
"Frame complete (FID bit toggled)\n");
buf->state = UVC_BUF_STATE_READY;
return -EAGAIN;
}
/*
* Some cameras, when running two parallel streams (one MJPEG alongside
* another non-MJPEG stream), are known to lose the EOF packet for a frame.
* We can detect the end of a frame by checking for a new SOI marker, as
* the SOI always lies on the packet boundary between two frames for
* these devices.
*/
if (stream->dev->quirks & UVC_QUIRK_MJPEG_NO_EOF &&
(stream->cur_format->fcc == V4L2_PIX_FMT_MJPEG ||
stream->cur_format->fcc == V4L2_PIX_FMT_JPEG) &&
buf && buf->bytesused != 0) {
const u8 *packet = data + header_len;
if (len >= header_len + 2 &&
packet[0] == 0xff && packet[1] == JPEG_MARKER_SOI) {
buf->state = UVC_BUF_STATE_READY;
buf->error = 1;
stream->last_fid ^= UVC_STREAM_FID;
return -EAGAIN;
}
}
/*
* Increase the sequence number regardless of any buffer states, so
* that discontinuous sequence numbers always indicate lost frames.
@ -1224,51 +1271,6 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
buf->state = UVC_BUF_STATE_ACTIVE;
}
/*
* Mark the buffer as done if we're at the beginning of a new frame.
* End of frame detection is better implemented by checking the EOF
* bit (FID bit toggling is delayed by one frame compared to the EOF
* bit), but some devices don't set the bit at end of frame (and the
* last payload can be lost anyway). We thus must check if the FID has
* been toggled.
*
* stream->last_fid is initialized to -1, so the first isochronous
* frame will never trigger an end of frame detection.
*
* Empty buffers (bytesused == 0) don't trigger end of frame detection
* as it doesn't make sense to return an empty buffer. This also
* avoids detecting end of frame conditions at FID toggling if the
* previous payload had the EOF bit set.
*/
if (fid != stream->last_fid && buf->bytesused != 0) {
uvc_dbg(stream->dev, FRAME,
"Frame complete (FID bit toggled)\n");
buf->state = UVC_BUF_STATE_READY;
return -EAGAIN;
}
/*
* Some cameras, when running two parallel streams (one MJPEG alongside
* another non-MJPEG stream), are known to lose the EOF packet for a frame.
* We can detect the end of a frame by checking for a new SOI marker, as
* the SOI always lies on the packet boundary between two frames for
* these devices.
*/
if (stream->dev->quirks & UVC_QUIRK_MJPEG_NO_EOF &&
(stream->cur_format->fcc == V4L2_PIX_FMT_MJPEG ||
stream->cur_format->fcc == V4L2_PIX_FMT_JPEG)) {
const u8 *packet = data + header_len;
if (len >= header_len + 2 &&
packet[0] == 0xff && packet[1] == JPEG_MARKER_SOI &&
buf->bytesused != 0) {
buf->state = UVC_BUF_STATE_READY;
buf->error = 1;
stream->last_fid ^= UVC_STREAM_FID;
return -EAGAIN;
}
}
stream->last_fid = fid;
return header_len;