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[media] uvcvideo: Fix V4L2 button controls that share the same UVC control

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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 <hdegoede@redhat.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Laurent Pinchart 2012-05-11 09:55:59 -03:00 committed by Mauro Carvalho Chehab
parent e2b710bfde
commit 6b363f9f97
1 changed files with 5 additions and 2 deletions
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7
drivers/media/video/uvc/uvc_ctrl.c
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@ -1351,9 +1351,12 @@ 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)