[PATCH v5 1/2] media: uvcvideo: Implement dual stream quirk to fix loss of usb packets

[Isaac Scott <isaac.scott@xxxxxxxxxxxxxxxx>]

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.

Signed-off-by: Isaac Scott <isaac.scott@xxxxxxxxxxxxxxxx>
---
 drivers/media/usb/uvc/uvc_video.c | 27 ++++++++++++++++++++++++++-
 drivers/media/usb/uvc/uvcvideo.h  |  1 +
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index e00f38dd07d9..028f16dc189a 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -21,6 +21,7 @@
 #include <linux/unaligned.h>
 
 #include <media/v4l2-common.h>
+#include <media/jpeg.h>
 
 #include "uvcvideo.h"
 
@@ -1117,6 +1118,7 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
 		struct uvc_buffer *buf, const u8 *data, int len)
 {
 	u8 fid;
+	u8 header_len;
 
 	/*
 	 * Sanity checks:
@@ -1129,6 +1131,8 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
 		return -EINVAL;
 	}
 
+	header_len = data[0];
+
 	fid = data[1] & UVC_STREAM_FID;
 
 	/*
@@ -1210,9 +1214,30 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
 		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.
+	 */
+	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 = ((const u8 *)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 data[0];
+	return header_len;
 }
 
 static inline enum dma_data_direction uvc_stream_dir(
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index b7d24a853ce4..116b1e383c25 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -76,6 +76,7 @@
 #define UVC_QUIRK_NO_RESET_RESUME	0x00004000
 #define UVC_QUIRK_DISABLE_AUTOSUSPEND	0x00008000
 #define UVC_QUIRK_INVALID_DEVICE_SOF	0x00010000
+#define UVC_QUIRK_MJPEG_NO_EOF          0x00020000
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001
-- 
2.43.0