According to the doc: The, in hindsight quite poor, solution for that is to set error_idx to count if the validation failed. Fixes v4l2-compliance: Control ioctls (Input 0): fail: v4l2-test-controls.cpp(645): invalid error index write only control test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> --- drivers/media/usb/uvc/uvc_v4l2.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c index 157310c0ca87..36eb48622d48 100644 --- a/drivers/media/usb/uvc/uvc_v4l2.c +++ b/drivers/media/usb/uvc/uvc_v4l2.c @@ -1073,7 +1073,8 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh, ret = uvc_ctrl_get(chain, ctrl); if (ret < 0) { uvc_ctrl_rollback(handle); - ctrls->error_idx = i; + ctrls->error_idx = (ret == -EACCES) ? + ctrls->count : i; return ret; } } -- 2.31.0.rc2.261.g7f71774620-goog