linux-kernel - [PATCH v4 5/5] media: uvcvideo: Use prio state from v4l2

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Message-Id: <20250616-uvc-fop-v4-5-250286570ee7@chromium.org>
Date: Mon, 16 Jun 2025 15:24:42 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hdegoede@...hat.com>, Hans Verkuil <hans@...erkuil.nl>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH v4 5/5] media: uvcvideo: Use prio state from v4l2_device

Currently, a UVC device can have multiple chains, and each chain maintains
its own priority state. While this behavior is technically correct for UVC,
uvcvideo is the *only* V4L2 driver that does not utilize the priority state
defined within `v4l2_device`.

This patch modifies uvcvideo to use the `v4l2_device` priority state. While
this might not be strictly "correct" for uvcvideo's multi-chain design, it
aligns uvcvideo with the rest of the V4L2 drivers, providing "correct enough"
behavior and enabling code cleanup in v4l2-core. Also, multi-chain
devices are extremely rare, they are typically implemented as two
independent usb devices.

Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 2 --
 drivers/media/usb/uvc/uvcvideo.h   | 1 -
 2 files changed, 3 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index accfb4ca3c72cb899185ddc8ecf4e29143d58fc6..e3795e40f14dc325e5bd120f5f45b60937841641 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1728,7 +1728,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
 	INIT_LIST_HEAD(&chain->entities);
 	mutex_init(&chain->ctrl_mutex);
 	chain->dev = dev;
-	v4l2_prio_init(&chain->prio);
 
 	return chain;
 }
@@ -2008,7 +2007,6 @@ int uvc_register_video_device(struct uvc_device *dev,
 	vdev->fops = fops;
 	vdev->ioctl_ops = ioctl_ops;
 	vdev->release = uvc_release;
-	vdev->prio = &stream->chain->prio;
 	vdev->queue = &queue->queue;
 	vdev->lock = &queue->mutex;
 	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 3e6d2d912f3a1cfcf63b2bc8edd3f86f3da305db..5ed9785d59c698cc7e0ac69955b892f932961617 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -354,7 +354,6 @@ struct uvc_video_chain {
 						 * uvc_fh.pending_async_ctrls
 						 */
 
-	struct v4l2_prio_state prio;		/* V4L2 priority state */
 	u32 caps;				/* V4L2 chain-wide caps */
 	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
 };

-- 
2.50.0.rc1.591.g9c95f17f64-goog