The Logitech pan/tilt reset UVC control contains two V4L2 button
controls to reset pan and tilt. As the UVC control is not marked as
auto-update, the button bits are set but never reset. A pan reset that
follows a tilt reset would thus reset both pan and tilt.
Fix this by not caching the control value of write-only controls. All
standard UVC controls are either readable or auto-update, so this will
not cause any regression and will not result in extra USB requests.
Reported-by: Hans de Goede <hdego...@redhat.com>
Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
---
drivers/media/video/uvc/uvc_ctrl.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/media/video/uvc/uvc_ctrl.c
b/drivers/media/video/uvc/uvc_ctrl.c
index 28363b7..3bc119b 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -1348,9 +1348,12 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
/* Reset the loaded flag for auto-update controls that were
* marked as loaded in uvc_ctrl_get/uvc_ctrl_set to prevent
- * uvc_ctrl_get from using the cached value.
+ * uvc_ctrl_get from using the cached value, and for write-only
+ * controls to prevent uvc_ctrl_set from setting bits not
+ * explicitly set by the user.
*/
- if (ctrl->info.flags & UVC_CTRL_FLAG_AUTO_UPDATE)
+ if (ctrl->info.flags & UVC_CTRL_FLAG_AUTO_UPDATE ||
+ !(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
ctrl->loaded = 0;
if (!ctrl->dirty)
--
1.7.3.4
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
