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;
+
+ if ((packet[0] == 0xff && packet[1] == 0xd8) && 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;
--
2.43.0
