Devices with pan/tilt controls but without pan/tilt speed controls return 1 for the default value of V4L2_CID_PAN_SPEED or V4L2_CID_TILT_SPEED. For these controls, the value of 1 means a move and that's not a good default. Currently, for these controls the UVC_GET_DEF query returns bPanSpeed or bTiltSpeed of CT_PANTILT_RELATIVE_CONTROL. According to the UVC 1.5 specification, the default value of bPanSpeed or bTiltSpeed should be 1 if the pan/tilt control doesn't support speed control. "If the control does not support speed control for the Tilt control, it will return the value 1 in this field for all these requests." This patch modifies the uvc_ctrl_get_rel_speed to return hardcoded 0 for UVC_GET_DEF query, because that's the stop or don't move value for these V4L2 controls. Previous discussion Link: https://lore.kernel.org/all/CAP_ceTy6XVmvTTAmvCp1YU2wxHwXqnarm69Yaz8K4FmpJqYxAg@xxxxxxxxxxxxxx/ Signed-off-by: Gergo Koteles <soyer@xxxxxx> --- drivers/media/usb/uvc/uvc_ctrl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index 5e9d3da862dd..e131958c0930 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -444,9 +444,10 @@ static s32 uvc_ctrl_get_rel_speed(struct uvc_control_mapping *mapping, return -data[first+1]; case UVC_GET_MAX: case UVC_GET_RES: + return data[first+1]; case UVC_GET_DEF: default: - return data[first+1]; + return 0; } } base-commit: be9aac187433af6abba5fcc2e73d91d0794ba360 -- 2.42.0
