media: uvcvideo: Allow changing noparam on the fly

Right now the parameter value is read during video_registration and
cannot be changed afterwards, despite its permissions 0644, that makes
the user believe that the value can be written.

The parameter only affects the behaviour of uvc_queue_buffer_complete(),
with only one check per buffer.

We can read the value directly from uvc_queue_buffer_complete() and
therefore allowing changing it with sysfs on the fly.

Signed-off-by: Ricardo Ribalda <[email protected]>
Reviewed-by: Laurent Pinchart <[email protected]>
Reviewed-by: Hans de Goede <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Laurent Pinchart <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

Author: ribalda

drivers/media/usb/uvc/uvc_driver.c

@@ -2024,7 +2024,7 @@ int uvc_register_video_device(struct uvc_device *dev,
 	int ret;
 
 	/* Initialize the video buffers queue. */
-	ret = uvc_queue_init(queue, type, !uvc_no_drop_param);
+	ret = uvc_queue_init(queue, type);
 	if (ret)
 		return ret;
 

drivers/media/usb/uvc/uvc_queue.c

@@ -208,8 +208,7 @@ static const struct vb2_ops uvc_meta_queue_qops = {
 	.stop_streaming = uvc_stop_streaming,
 };
 
-int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
-		    int drop_corrupted)
+int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
 {
 	int ret;
 
@@ -239,7 +238,6 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
 	mutex_init(&queue->mutex);
 	spin_lock_init(&queue->irqlock);
 	INIT_LIST_HEAD(&queue->irqqueue);
-	queue->flags = drop_corrupted ? UVC_QUEUE_DROP_CORRUPTED : 0;
 
 	return 0;
 }
@@ -472,7 +470,7 @@ static void uvc_queue_buffer_complete(struct kref *ref)
 	struct vb2_buffer *vb = &buf->buf.vb2_buf;
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
 
-	if ((queue->flags & UVC_QUEUE_DROP_CORRUPTED) && buf->error) {
+	if (buf->error && !uvc_no_drop_param) {
 		uvc_queue_buffer_requeue(queue, buf);
 		return;
 	}

drivers/media/usb/uvc/uvcvideo.h

@@ -317,7 +317,6 @@ struct uvc_buffer {
 };
 
 #define UVC_QUEUE_DISCONNECTED		(1 << 0)
-#define UVC_QUEUE_DROP_CORRUPTED	(1 << 1)
 
 struct uvc_video_queue {
 	struct vb2_queue queue;
@@ -680,8 +679,7 @@ extern struct uvc_driver uvc_driver;
 struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
 
 /* Video buffers queue management. */
-int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
-		   int drop_corrupted);
+int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
 void uvc_queue_release(struct uvc_video_queue *queue);
 int uvc_request_buffers(struct uvc_video_queue *queue,
 			struct v4l2_requestbuffers *rb);