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Message-ID: <20251113215909.GG9135@pendragon.ideasonboard.com>
Date: Thu, 13 Nov 2025 23:59:09 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Hans de Goede <hansg@...nel.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Hans Verkuil <hverkuil@...nel.org>, Yunke Cao <yunkec@...gle.com>,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Subject: Re: [PATCH] media: uvcvideo: Fix support for
V4L2_CTRL_FLAG_HAS_WHICH_MIN_MAX
Hi Ricardo,
Thank you for the patch.
On Tue, Oct 28, 2025 at 05:55:10PM +0000, Ricardo Ribalda wrote:
> The VIDIOC_G_EXT_CTRLS with which V4L2_CTRL_WHICH_(MIN|MAX)_VAL can only
> work for controls that have previously announced support for it.
>
> This patch fixes the following v4l2-compliance error:
>
> info: checking extended control 'User Controls' (0x00980001)
> fail: v4l2-test-controls.cpp(980): ret != EINVAL (got 13)
> test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL
>
> Fixes: 39d2c891c96e ("media: uvcvideo: support V4L2_CTRL_WHICH_MIN/MAX_VAL")
> Cc: stable@...r.kernel.org
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 11 +++++++++--
> drivers/media/usb/uvc/uvc_v4l2.c | 9 ++++++---
> drivers/media/usb/uvc/uvcvideo.h | 2 +-
> 3 files changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 2905505c240c060e5034ea12d33b59d5702f2e1f..2f7d5cdd18e072a47fb5906da0f847dd449911b4 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1432,7 +1432,7 @@ static bool uvc_ctrl_is_readable(u32 which, struct uvc_control *ctrl,
> * auto_exposure=1, exposure_time_absolute=251.
> */
> int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> - const struct v4l2_ext_controls *ctrls,
> + const struct v4l2_ext_controls *ctrls, u32 which,
> unsigned long ioctl)
> {
> struct uvc_control_mapping *master_map = NULL;
> @@ -1442,14 +1442,21 @@ int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> s32 val;
> int ret;
> int i;
> + bool is_which_min_max = (ioctl == VIDIOC_G_EXT_CTRLS &&
Is the ioctl check needed, given that this function will be called with
which set to V4L2_CTRL_WHICH_CUR_VAL if ioctl is not VIDIOC_G_EXT_CTRLS
?
> + (which == V4L2_CTRL_WHICH_MIN_VAL ||
> + which == V4L2_CTRL_WHICH_MAX_VAL));
Let's move this up to have longer lines first.
>
> if (__uvc_query_v4l2_class(chain, v4l2_id, 0) >= 0)
> - return -EACCES;
> + return is_which_min_max ? -EINVAL : -EACCES;
>
> ctrl = uvc_find_control(chain, v4l2_id, &mapping);
> if (!ctrl)
> return -EINVAL;
>
> + if ((!(ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX) ||
> + !(ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)) && is_which_min_max)
Please put MIN before MAX.
Do we have to bundle min and max, or could we handle them separately ?
Something like
if ((which == V4L2_CTRL_WHICH_MIN_VAL &&
!(ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)) ||
(which == V4L2_CTRL_WHICH_M1X_VAL &&
!(ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)))
return -EINVAL;
> + return -EINVAL;
> +
> if (ioctl == VIDIOC_G_EXT_CTRLS)
> return uvc_ctrl_is_readable(ctrls->which, ctrl, mapping);
>
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 9e4a251eca88085a1b4e0e854370015855be92ee..d5274dc94da3c60f1f4566b307dd445f30c4f45f 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -765,6 +765,7 @@ static int uvc_ioctl_query_ext_ctrl(struct file *file, void *priv,
>
> static int uvc_ctrl_check_access(struct uvc_video_chain *chain,
> struct v4l2_ext_controls *ctrls,
> + u32 which,
This fits on the previous line.
> unsigned long ioctl)
> {
> struct v4l2_ext_control *ctrl = ctrls->controls;
> @@ -772,7 +773,8 @@ static int uvc_ctrl_check_access(struct uvc_video_chain *chain,
> int ret = 0;
>
> for (i = 0; i < ctrls->count; ++ctrl, ++i) {
> - ret = uvc_ctrl_is_accessible(chain, ctrl->id, ctrls, ioctl);
> + ret = uvc_ctrl_is_accessible(chain, ctrl->id, ctrls, which,
> + ioctl);
> if (ret)
> break;
> }
> @@ -806,7 +808,7 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *priv,
> which = V4L2_CTRL_WHICH_CUR_VAL;
> }
>
> - ret = uvc_ctrl_check_access(chain, ctrls, VIDIOC_G_EXT_CTRLS);
> + ret = uvc_ctrl_check_access(chain, ctrls, which, VIDIOC_G_EXT_CTRLS);
> if (ret < 0)
> return ret;
>
> @@ -840,7 +842,8 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
> if (!ctrls->count)
> return 0;
>
> - ret = uvc_ctrl_check_access(chain, ctrls, ioctl);
> + ret = uvc_ctrl_check_access(chain, ctrls, V4L2_CTRL_WHICH_CUR_VAL,
> + ioctl);
> if (ret < 0)
> return ret;
>
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index ed7bad31f75ca474c1037d666d5310c78dd764df..d583425893a5f716185153a07aae9bfe20182964 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -786,7 +786,7 @@ int uvc_ctrl_get(struct uvc_video_chain *chain, u32 which,
> struct v4l2_ext_control *xctrl);
> int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl);
> int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> - const struct v4l2_ext_controls *ctrls,
> + const struct v4l2_ext_controls *ctrls, u32 which,
> unsigned long ioctl);
>
> int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
>
> ---
> base-commit: c218ce4f98eccf5a40de64c559c52d61e9cc78ee
> change-id: 20251028-uvc-fix-which-c3ba1fb68ed5
--
Regards,
Laurent Pinchart
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