V4L/DVB (9809): uvcvideo: Add nodrop module parameter to turn incomplete frame drop off.

The driver drops incomplete uncompressed video frames to avoid confusing
userspace with corrupt data. Add a nodrop module parameter to turn that
behaviour off and make all frames available to userspace.
Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/uvc/uvc_driver.c

@@ -44,6 +44,7 @@
 #define DRIVER_VERSION		"v0.1.0"
 #endif
 
+unsigned int uvc_no_drop_param;
 static unsigned int uvc_quirks_param;
 unsigned int uvc_trace_param;
 
@@ -1939,6 +1940,8 @@ static void __exit uvc_cleanup(void)
 module_init(uvc_init);
 module_exit(uvc_cleanup);
 
+module_param_named(nodrop, uvc_no_drop_param, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(nodrop, "Don't drop incomplete frames");
 module_param_named(quirks, uvc_quirks_param, uint, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(quirks, "Forced device quirks");
 module_param_named(trace, uvc_trace_param, uint, S_IRUGO|S_IWUSR);

drivers/media/video/uvc/uvc_video.c

@@ -1003,7 +1003,8 @@ int uvc_video_enable(struct uvc_video_device *video, int enable)
 		return 0;
 	}
 
-	if (video->streaming->cur_format->flags & UVC_FMT_FLAG_COMPRESSED)
+	if ((video->streaming->cur_format->flags & UVC_FMT_FLAG_COMPRESSED) ||
+	    uvc_no_drop_param)
 		video->queue.flags &= ~UVC_QUEUE_DROP_INCOMPLETE;
 	else
 		video->queue.flags |= UVC_QUEUE_DROP_INCOMPLETE;

drivers/media/video/uvc/uvcvideo.h

@@ -683,6 +683,7 @@ struct uvc_driver {
 #define UVC_WARN_MINMAX		0
 #define UVC_WARN_PROBE_DEF	1
 
+extern unsigned int uvc_no_drop_param;
 extern unsigned int uvc_trace_param;
 
 #define uvc_trace(flag, msg...) \