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SubjectRe: [PATCH v10 21/21] media: uvcvideo: Return -EACCES to inactive controls
Hi Hans

Did you have some hardware that did not work fine without this patch?
Am I remembering correctly?

Thanks!

On Fri, 18 Jun 2021 at 14:29, Ricardo Ribalda <ribalda@chromium.org> wrote:
>
> If a control is inactive return -EACCES to let the userspace know that
> the value will not be applied automatically when the control is active
> again.
>
> Also make sure that query_v4l2_ctrl doesn't return an error.
>
> Suggested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 73 +++++++++++++++++++++-----------
> 1 file changed, 49 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index da44d5c0b9ad..4f80c06d3c43 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1104,13 +1104,36 @@ static const char *uvc_map_get_name(const struct uvc_control_mapping *map)
> return "Unknown Control";
> }
>
> +static bool uvc_ctrl_is_inactive(struct uvc_video_chain *chain,
> + struct uvc_control *ctrl,
> + struct uvc_control_mapping *mapping)
> +{
> + struct uvc_control_mapping *master_map = NULL;
> + struct uvc_control *master_ctrl = NULL;
> + s32 val;
> + int ret;
> +
> + if (!mapping->master_id)
> + return false;
> +
> + __uvc_find_control(ctrl->entity, mapping->master_id, &master_map,
> + &master_ctrl, 0);
> +
> + if (!master_ctrl || !(master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
> + return false;
> +
> + ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> + if (ret < 0 || val == mapping->master_manual)
> + return false;
> +
> + return true;
> +}
> +
> static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> struct uvc_control *ctrl,
> struct uvc_control_mapping *mapping,
> struct v4l2_queryctrl *v4l2_ctrl)
> {
> - struct uvc_control_mapping *master_map = NULL;
> - struct uvc_control *master_ctrl = NULL;
> const struct uvc_menu_info *menu;
> unsigned int i;
>
> @@ -1126,18 +1149,8 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
> v4l2_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>
> - if (mapping->master_id)
> - __uvc_find_control(ctrl->entity, mapping->master_id,
> - &master_map, &master_ctrl, 0);
> - if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
> - s32 val;
> - int ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> - if (ret < 0)
> - return ret;
> -
> - if (val != mapping->master_manual)
> - v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> - }
> + if (uvc_ctrl_is_inactive(chain, ctrl, mapping))
> + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
>
> if (!ctrl->cached) {
> int ret = uvc_ctrl_populate_cache(chain, ctrl);
> @@ -1660,25 +1673,37 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
> return 0;
> }
>
> -static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
> - struct v4l2_ext_controls *ctrls,
> - struct uvc_control *uvc_control)
> +static int uvc_ctrl_commit_error(struct uvc_video_chain *chain,
> + struct uvc_entity *entity,
> + struct v4l2_ext_controls *ctrls,
> + struct uvc_control *err_control,
> + int ret)
> {
> struct uvc_control_mapping *mapping;
> struct uvc_control *ctrl_found;
> unsigned int i;
>
> - if (!entity)
> - return ctrls->count;
> + if (!entity) {
> + ctrls->error_idx = ctrls->count;
> + return ret;
> + }
>
> for (i = 0; i < ctrls->count; i++) {
> __uvc_find_control(entity, ctrls->controls[i].id, &mapping,
> &ctrl_found, 0);
> - if (uvc_control == ctrl_found)
> - return i;
> + if (err_control == ctrl_found)
> + break;
> }
> + ctrls->error_idx = i;
> +
> + /* We could not find the control that failed. */
> + if (i == ctrls->count)
> + return ret;
> +
> + if (uvc_ctrl_is_inactive(chain, err_control, mapping))
> + return -EACCES;
>
> - return ctrls->count;
> + return ret;
> }
>
> int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> @@ -1701,8 +1726,8 @@ int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> uvc_ctrl_send_events(handle, ctrls->controls, ctrls->count);
> done:
> if (ret < 0 && ctrls)
> - ctrls->error_idx = uvc_ctrl_find_ctrl_idx(entity, ctrls,
> - err_ctrl);
> + ret = uvc_ctrl_commit_error(chain, entity, ctrls, err_ctrl,
> + ret);
> mutex_unlock(&chain->ctrl_mutex);
> return ret;
> }
> --
> 2.32.0.288.g62a8d224e6-goog
>


--
Ricardo Ribalda

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