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.pinch...@ideasonboard.com>
---
drivers/media/video/uvc/uvc_ctrl.c | 17 +++++++++++++++--
drivers/media/video/uvc/uvcvideo.h | 1 +
2 files changed, 16 insertions(+), 2 deletions(-)
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 @@ static int uvc_ctrl_populate_cache(struct uvc_video_chain
*chain,
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;
diff --git a/drivers/media/video/uvc/uvcvideo.h
b/drivers/media/video/uvc/uvcvideo.h
index 882159a..2b84cbb 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -477,6 +477,7 @@ struct uvc_driver {
#define UVC_WARN_MINMAX 0
#define UVC_WARN_PROBE_DEF 1
+#define UVC_WARN_XU_GET_RES 2
extern unsigned int uvc_clock_param;
extern unsigned int uvc_no_drop_param;
--
1.7.3.4
--
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