On Fri, 8 Nov 2024 at 15:24, Isaac Scott <isaac.scott@xxxxxxxxxxxxxxxx> wrote:
>
> Some cameras, such as the Sonix Technology Co. 292A exhibit issues when
> running two parallel streams, causing USB packets to be dropped when an
> H.264 stream posts a keyframe while an MJPEG stream is running
> simultaneously. This occasionally causes the driver to erroneously
> output two consecutive JPEG images as a single frame.
>
> To fix this, we inspect the buffer, and trigger a new frame when we
> find an SOI, inverting the FID to make sure no frames are erroneously
> dropped.
>
> Signed-off-by: Isaac Scott <isaac.scott@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/usb/uvc/uvc_video.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index 2fb9f2b59afc..f754109f5e96 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1211,6 +1211,30 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
> return -EAGAIN;
> }
>
> + /*
> + * Some cameras, such as the Sonix Technology Co. 292A exhibit issues
> + * when running two parallel streams, causing USB packets to be dropped
> + * when an H.264 stream posts a keyframe while an MJPEG stream is
> + * running simultaneously. This occasionally causes the driver to
> + * erroneously output two consecutive JPEG images as a single frame.
> + *
> + * Check the buffer for a new SOI on JPEG streams and complete the
> + * preceding buffer using EAGAIN, and invert the FID to make sure the
> + * erroneous frame is not dropped.
> + */
> + 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;
Don't you have to validate that data[header_len+1]
can be read?
> +
> + if ((packet[0] == 0xff && packet[1] == 0xd8) && buf->bytesused != 0) {
nit: maybe it would be nice to make a define for 0xd8 and say what it is
> + buf->state = UVC_BUF_STATE_READY;
> + buf->error = 1;
> + stream->last_fid ^= UVC_STREAM_FID;
> + return -EAGAIN;
> + }
> + }
> +
> stream->last_fid = fid;
>
> return header_len;
> --
> 2.43.0
>
>
--
Ricardo Ribalda
