media: uvcvideo: Override default flags

When the UVC device has a control that is readonly it doesn't set the
SET_CUR flag. For example the privacy control has SET_CUR flag set in
the defaults in the `uvc_ctrls` variable. Even if the device does not
have it set, it's not cleared by uvc_ctrl_get_flags().

Originally written with assignment in commit 859086ae3636 ("media:
uvcvideo: Apply flags from device to actual properties"). But changed to
|= in commit 0dc68cabdb62 ("media: uvcvideo: Prevent setting unavailable
flags"). It would not clear the default flags.

With this patch applied the correct flags are reported to user space.
Tested with:

```
> v4l2-ctl --list-ctrls | grep privacy
privacy 0x009a0910 (bool)   : default=0 value=0 flags=read-only
```

Signed-off-by: Daniel Schaefer <dhs@frame.work>
Fixes: 0dc68cabdb62 ("media: uvcvideo: Prevent setting unavailable flags")
Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20240602065053.36850-1-dhs@frame.work
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 4b685f883e4d71f79646cdc94b0e8b56120da62e..a7d0ec22d95c05c166d38265a4f01ff8266db99f 100644 (file)
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -2031,7 +2031,13 @@ static int uvc_ctrl_get_flags(struct uvc_device *dev,
        else
                ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id,
                                     dev->intfnum, info->selector, data, 1);
-       if (!ret)
+
+       if (!ret) {
+               info->flags &= ~(UVC_CTRL_FLAG_GET_CUR |
+                                UVC_CTRL_FLAG_SET_CUR |
+                                UVC_CTRL_FLAG_AUTO_UPDATE |
+                                UVC_CTRL_FLAG_ASYNCHRONOUS);
+
                info->flags |= (data[0] & UVC_CONTROL_CAP_GET ?
                                UVC_CTRL_FLAG_GET_CUR : 0)
                            |  (data[0] & UVC_CONTROL_CAP_SET ?
@@ -2040,6 +2046,7 @@ static int uvc_ctrl_get_flags(struct uvc_device *dev,
                                UVC_CTRL_FLAG_AUTO_UPDATE : 0)
                            |  (data[0] & UVC_CONTROL_CAP_ASYNCHRONOUS ?
                                UVC_CTRL_FLAG_ASYNCHRONOUS : 0);
+       }
 
        kfree(data);
        return ret;