On Tue, 3 Dec 2024 at 21:38, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > > On Mon, Dec 02, 2024 at 03:45:57PM +0100, Hans de Goede wrote: > > Hi, > > > > On 2-Dec-24 3:24 PM, Ricardo Ribalda wrote: > > > Asynchronous controls trigger an event when they have completed their > > > operation. > > > > > > This can make that the control cached value does not match the value in > > > the device. > > > > > > Let's flush the cache to be on the safe side. > > > > > > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> > > > --- > > > drivers/media/usb/uvc/uvc_ctrl.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > > > index e90bf2aeb5e4..75d534072f50 100644 > > > --- a/drivers/media/usb/uvc/uvc_ctrl.c > > > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > > > @@ -1672,6 +1672,9 @@ bool uvc_ctrl_status_event_async(struct urb *urb, struct uvc_video_chain *chain, > > > struct uvc_device *dev = chain->dev; > > > struct uvc_ctrl_work *w = &dev->async_ctrl; > > > > > > + /* Flush the control cache, the data might have changed. */ > > > + ctrl->loaded = 0; > > > + > > > if (list_empty(&ctrl->info.mappings)) > > > return false; > > > > > > > Thank you for the patch. > > > > I'm not familiar enough with UVC yet to really have an opinion on this one, > > so I'll defer reviewing this one to Laurent. > > Conceptually this change looks fine, but the commit message needs to > explain why this is safe to do without protecting ctrl->loaded with a > lock. Just realised that loaded is a bit field... and we shall not be creative with lockless writes with those. I am going to move it to uvc_ctrl_status_event(). It will not work with controls without mappings... but I guess we do not care about the cache for those. Feel free to land the whole series without this patch if we need further discussion or changes. > > -- > Regards, > > Laurent Pinchart -- Ricardo Ribalda
