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Message-ID: <fe050465-eb6f-42cc-85c3-07c45f948dec@redhat.com>
Date: Mon, 7 Apr 2025 15:48:15 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: Ricardo Ribalda <ribalda@...omium.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil <hverkuil@...all.nl>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7] media: uvcvideo: Set V4L2_CTRL_FLAG_DISABLED during
queryctrl errors
Hi,
On 3-Apr-25 14:59, Ricardo Ribalda wrote:
> To implement VIDIOC_QUERYCTRL, we need to know the minimum, maximum,
> step and flags of the control. For some of the controls, this involves
> querying the actual hardware.
>
> Some non-compliant cameras produce errors when we query them. These
> error can be triggered every time, sometimes, or when other controls do
> not have the "right value". Right now, we populate that error to userspace.
> When an error happens, the v4l2 framework does not copy the v4l2_queryctrl
> struct to userspace. Also, userspace apps are not ready to handle any
> other error than -EINVAL.
>
> One of the main usecases of VIDIOC_QUERYCTRL is enumerating the controls
> of a device. This is done using the V4L2_CTRL_FLAG_NEXT_CTRL flag. In
> that usecase, a non-compliant control will make it almost impossible to
> enumerate all controls of the device.
>
> A control with an invalid max/min/step/flags is better than non being
> able to enumerate the rest of the controls.
>
> This patch:
> - Retries for an extra attempt to read the control, to avoid spurious
> errors. More attempts do not seem to produce better results in the
> tested hardware.
> - Makes VIDIOC_QUERYCTRL return 0 in all the error cases different than
> -EINVAL.
> - Introduces a warning in dmesg so we can have a trace of what has happened
> and sets the V4L2_CTRL_FLAG_DISABLED.
> - Makes sure we keep returning V4L2_CTRL_FLAG_DISABLED for all the next
> attempts to query that control (other operations have the same
> functionality as now).
>
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
Thanks, patch looks good to me:
Reviewed-by: Hans de Goede <hdegoede@...hat.com>
Hans Verkuil, are you happy with this patch now that Ricardo has provided
updated v4l2-ctl output ?
Regards,
Hans
> ---
> Hi 2*Hans and Laurent!
>
> I came around a device that was listing just a couple of controls when
> it should be listing much more.
>
> Some debugging later I found that the device was returning -EIO when
> all the focal controls were read.
>
> Lots of good arguments in favor/against this patch in the v1. Please
> check!
>
> Without this patch:
> $ v4l2-ctl --list-ctrls
> User Controls
>
> brightness 0x00980900 (int) : min=0 max=255 step=1 default=128 value=128
> contrast 0x00980901 (int) : min=0 max=100 step=1 default=32 value=32
> saturation 0x00980902 (int) : min=0 max=100 step=1 default=64 value=64
> hue 0x00980903 (int) : min=-180 max=180 step=1 default=0 value=0
> white_balance_automatic 0x0098090c (bool) : default=1 value=1
> gamma 0x00980910 (int) : min=90 max=150 step=1 default=120 value=120
> power_line_frequency 0x00980918 (menu) : min=0 max=2 default=2 value=2 (60 Hz)
> white_balance_temperature 0x0098091a (int) : min=2800 max=6500 step=1 default=4600 value=4600 flags=inactive
>
> With this patch:
> $ v4l2-ctl --list-ctrls
>
> User Controls
>
> brightness 0x00980900 (int) : min=0 max=255 step=1 default=128 value=128
> contrast 0x00980901 (int) : min=0 max=100 step=1 default=32 value=32
> saturation 0x00980902 (int) : min=0 max=100 step=1 default=64 value=64
> hue 0x00980903 (int) : min=-180 max=180 step=1 default=0 value=0
> white_balance_automatic 0x0098090c (bool) : default=1 value=1
> gamma 0x00980910 (int) : min=90 max=150 step=1 default=120 value=120
> power_line_frequency 0x00980918 (menu) : min=0 max=2 default=2 value=2 (60 Hz)
> white_balance_temperature 0x0098091a (int) : min=2800 max=6500 step=1 default=4600 value=4600 flags=inactive
> sharpness 0x0098091b (int) : min=0 max=7 step=1 default=3 value=3
> backlight_compensation 0x0098091c (int) : min=0 max=2 step=1 default=1 value=1
> [ 32.777643] usb 3-6: UVC non compliance: permanently disabling control 98091b (Sharpness), due to error -5
>
> Camera Controls
>
> auto_exposure 0x009a0901 (menu) : min=0 max=3 default=3 value=3 (Aperture Priority Mode)
> exposure_time_absolute 0x009a0902 (int) : min=2 max=1250 step=1 default=156 value=156 flags=inactive
> exposure_dynamic_framerate 0x009a0903 (bool) : default=0 value=0
> privacy 0x009a0910 (bool) : default=0 value=0 flags=read-only
> region_of_interest_rectangle 0x009a1901 (unknown): type=107 value=unsupported payload type flags=has-payload
> region_of_interest_auto_ctrls 0x009a1902 (bitmask): max=0x00000001 default=0x00000001 value=1
>
> Emulating error with:
> + if (cs == UVC_PU_SHARPNESS_CONTROL && query == UVC_GET_MAX) {
> + printk(KERN_ERR "%s:%d %s\n", __FILE__, __LINE__, __func__);
> + return -EIO;
> + }
> In uvc_query_ctrl()
> ---
> Changes in v7:
> - Only retry on -EIO (Thanks Hans).
> - Add comment for retry (Thanks Hans).
> - Rebase patch
> - Check master_map->disabled before reading the master control.
> - Link to v6: https://lore.kernel.org/r/20250310-uvc-eaccess-v6-1-bf4562f7cabd@chromium.org
>
> Changes in v6:
> - Keep returning V4L2_CTRL_FLAG_DISABLED in future control queries.
> - Link to v5: https://lore.kernel.org/r/20250224-uvc-eaccess-v5-1-690d73bcef28@chromium.org
>
> Changes in v5:
> - Explain the retry in the commit message (Thanks Laurent).
> - Link to v4: https://lore.kernel.org/r/20250111-uvc-eaccess-v4-1-c7759bfd1bd4@chromium.org
>
> Changes in v4:
> - Display control name (Thanks Hans)
> - Link to v3: https://lore.kernel.org/r/20250107-uvc-eaccess-v3-1-99f3335d5133@chromium.org
>
> Changes in v3:
> - Add a retry mechanism during error.
> - Set V4L2_CTRL_FLAG_DISABLED flag.
> - Link to v2: https://lore.kernel.org/r/20241219-uvc-eaccess-v2-1-bf6520c8b86d@chromium.org
>
> Changes in v2:
> - Never return error, even if we are not enumerating the controls
> - Improve commit message.
> - Link to v1: https://lore.kernel.org/r/20241213-uvc-eaccess-v1-1-62e0b4fcc634@chromium.org
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 53 ++++++++++++++++++++++++++++++++++------
> drivers/media/usb/uvc/uvcvideo.h | 2 ++
> 2 files changed, 47 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index cbf19aa1d82374a08cf79b6a6787fa348b83523a..b41fed364d54aefd7da72c47197cf9d9e3c1b176 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1483,14 +1483,28 @@ static u32 uvc_get_ctrl_bitmap(struct uvc_control *ctrl,
> return ~0;
> }
>
> +/*
> + * Maximum retry count to avoid spurious errors with controls. Increase this
> + * value does no seem to produce better results in the tested hardware.
> + */
> +#define MAX_QUERY_RETRIES 2
> +
> static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain,
> struct uvc_control *ctrl,
> struct uvc_control_mapping *mapping,
> struct v4l2_query_ext_ctrl *v4l2_ctrl)
> {
> if (!ctrl->cached) {
> - int ret = uvc_ctrl_populate_cache(chain, ctrl);
> - if (ret < 0)
> + unsigned int retries;
> + int ret;
> +
> + for (retries = 0; retries < MAX_QUERY_RETRIES; retries++) {
> + ret = uvc_ctrl_populate_cache(chain, ctrl);
> + if (ret != -EIO)
> + break;
> + }
> +
> + if (ret)
> return ret;
> }
>
> @@ -1567,6 +1581,7 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> {
> struct uvc_control_mapping *master_map = NULL;
> struct uvc_control *master_ctrl = NULL;
> + int ret;
>
> memset(v4l2_ctrl, 0, sizeof(*v4l2_ctrl));
> v4l2_ctrl->id = mapping->id;
> @@ -1587,18 +1602,29 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> __uvc_find_control(ctrl->entity, mapping->master_id,
> &master_map, &master_ctrl, 0, 0);
> if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
> + unsigned int retries;
> s32 val;
> int ret;
>
> if (WARN_ON(uvc_ctrl_mapping_is_compound(master_map)))
> return -EIO;
>
> - ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> - if (ret < 0)
> - return ret;
> + for (retries = 0; retries < MAX_QUERY_RETRIES; retries++) {
> + ret = __uvc_ctrl_get(chain, master_ctrl, master_map,
> + &val);
> + if (ret != -EIO)
> + break;
> + }
>
> - if (val != mapping->master_manual)
> - v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> + if (ret < 0) {
> + dev_warn_ratelimited(&chain->dev->udev->dev,
> + "UVC non compliance: Error %d querying master control %x (%s)\n",
> + ret, master_map->id,
> + uvc_map_get_name(master_map));
> + } else {
> + if (val != mapping->master_manual)
> + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> + }
> }
>
> v4l2_ctrl->elem_size = uvc_mapping_v4l2_size(mapping);
> @@ -1613,7 +1639,18 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> return 0;
> }
>
> - return __uvc_queryctrl_boundaries(chain, ctrl, mapping, v4l2_ctrl);
> + ret = __uvc_queryctrl_boundaries(chain, ctrl, mapping, v4l2_ctrl);
> + if (ret && !mapping->disabled) {
> + dev_warn(&chain->dev->udev->dev,
> + "UVC non compliance: permanently disabling control %x (%s), due to error %d\n",
> + mapping->id, uvc_map_get_name(mapping), ret);
> + mapping->disabled = true;
> + }
> +
> + if (mapping->disabled)
> + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_DISABLED;
> +
> + return 0;
> }
>
> int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index b4ee701835fc016474d2cd2a0b67b2aa915c1c60..8e3753896d42baddcc2192057e8c5786ddd79fa8 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -134,6 +134,8 @@ struct uvc_control_mapping {
> s32 master_manual;
> u32 slave_ids[2];
>
> + bool disabled;
> +
> const struct uvc_control_mapping *(*filter_mapping)
> (struct uvc_video_chain *chain,
> struct uvc_control *ctrl);
>
> ---
> base-commit: 4e82c87058f45e79eeaa4d5bcc3b38dd3dce7209
> change-id: 20250403-uvc-eaccess-8f3666151830
>
> Best regards,
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