6.15-stable review patch. If anyone has any objections, please let me know.
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From: Ricardo Ribalda ribalda@chromium.org
[ Upstream commit 649c033711d7fd6e1d5d69e4cfc3fceca7de2867 ]
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 for -EIO errors. - 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).
Reviewed-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Ricardo Ribalda ribalda@chromium.org Link: https://lore.kernel.org/r/20250502-uvc-eaccess-v8-1-0b8b58ac1142@chromium.or... Signed-off-by: Hans de Goede hansg@kernel.org Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Hans Verkuil hverkuil@xs4all.nl Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/usb/uvc/uvc_ctrl.c | 55 +++++++++++++++++++++++++++----- drivers/media/usb/uvc/uvcvideo.h | 2 ++ 2 files changed, 49 insertions(+), 8 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index 44b6513c5264..f24272d483a2 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. Increasing 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 +1602,31 @@ 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) + break; + if (ret < 0 && ret != -EIO) + return ret; + }
- if (val != mapping->master_manual) - v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE; + if (ret == -EIO) { + 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 +1641,18 @@ 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 b9f8eb62ba1d..11d6e3c2ebdf 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);