Re: [PATCH] media: uvcvideo: Implement V4L2_EVENT_FRAME_SYNC

From: Laurent Pinchart
Date: Mon Nov 06 2023 - 05:59:39 EST


On Mon, Nov 06, 2023 at 11:51:06AM +0100, Ricardo Ribalda wrote:
> On Mon, 6 Nov 2023 at 11:42, Laurent Pinchart wrote:
> > On Mon, Nov 06, 2023 at 12:39:26PM +0200, Laurent Pinchart wrote:
> > > On Fri, Oct 20, 2023 at 06:41:45AM +0000, Ricardo Ribalda wrote:
> > > > Add support for the frame_sync event, so user-space can become aware
> > > > earlier of new frames.
> > > >
> > > > Suggested-by: Esker Wong <esker@xxxxxxxxxxxx>
> > > > Tested-by: Esker Wong <esker@xxxxxxxxxxxx>
> > > > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> > > > ---
> > > > We have measured a latency of around 30msecs between frame sync
> > > > and dqbuf.
> > >
> > > Not surprising, especially for large resolutions. I'm curious though,
> > > what do you use this event for ?
>
> I think Esker is using it to get more accurate power measurements of
> the camera stack.

Esker, would you be able to provide more information ?

> > > It's easy to miss the ++ there when reading the code, would the
> > > following be more readable ?
>
> Actually that was my original code, but I thought you would like this better :)
>
> Thanks for the review, a v2 is on its way.

Thank you.

--
Regards,

Laurent Pinchart