[media] uvcvideo: Ignore GET_RES error for XU controls
GET_RES request support is mandatory for extension units, but some
cameras still choke on it (one example is the Logitech QuickCam PTZ that
returns a single byte for the PTZ relative control instead of four).
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index 254d326..3e849d9 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -878,8 +878,21 @@
chain->dev->intfnum, ctrl->info.selector,
uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES),
ctrl->info.size);
- if (ret < 0)
- return ret;
+ if (ret < 0) {
+ if (UVC_ENTITY_TYPE(ctrl->entity) !=
+ UVC_VC_EXTENSION_UNIT)
+ return ret;
+
+ /* GET_RES is mandatory for XU controls, but some
+ * cameras still choke on it. Ignore errors and set the
+ * resolution value to zero.
+ */
+ uvc_warn_once(chain->dev, UVC_WARN_XU_GET_RES,
+ "UVC non compliance - GET_RES failed on "
+ "an XU control. Enabling workaround.\n");
+ memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES), 0,
+ ctrl->info.size);
+ }
}
ctrl->cached = 1;