linux-kernel - [PATCH v2 3/4] media: uvcvideo: Allow changing noparam on the fly

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Message-Id: <20241218-uvc-deprecate-v2-3-ab814139e983@chromium.org>
Date: Wed, 18 Dec 2024 21:39:10 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hdegoede@...hat.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH v2 3/4] 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 beviour 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 <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 2 +-
 drivers/media/usb/uvc/uvc_queue.c  | 6 ++----
 drivers/media/usb/uvc/uvcvideo.h   | 4 +---
 3 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 091145743872..10812a841587 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1995,7 +1995,7 @@ 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;
 
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index f8464f0aae1b..2ee142621042 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/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;
 	}
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 07f9921d83f2..ebbd8afcf136 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -316,7 +316,6 @@ struct uvc_buffer {
 };
 
 #define UVC_QUEUE_DISCONNECTED		(1 << 0)
-#define UVC_QUEUE_DROP_CORRUPTED	(1 << 1)
 
 struct uvc_video_queue {
 	struct vb2_queue queue;
@@ -674,8 +673,7 @@ 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);

-- 
2.47.1.613.gc27f4b7a9f-goog