[libcamera-devel] [PATCH] v4l2: v4l2_camera_proxy: Fix timestamp calculation

[Kieran Bingham]

Quoting Laurent Pinchart (2022-02-15 06:42:13)
> Hi Kieran,
> 
> Thank you for the patch.
> 
> On Mon, Feb 14, 2022 at 12:39:51PM +0000, Kieran Bingham wrote:
> > The V4L2 Compatibility layer is returning timestamps for buffers which
> > are incorrectly calculated from the frame metadata.
> > 
> > The sec component of the timestamp is correct, but the nsec component is
> 
> Did you mean usec ?

Yes, it seems my commit message is out by the same order of magnitude as
the bug ...

Fixed,

> > out, leaving frame captures reporting non-monotonically increasing
> > timestamps, and incorrect frame rate calculations.
> > 
> > Fix the usecs calculation reported by the V4L2 adaptation layer.
> > 
> > Bug: https://bugs.libcamera.org/show_bug.cgi?id=118
> > Fixes: 0ce8f2390b52 ("v4l2: v4l2_compat: Add V4L2 compatibility layer")
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> >  src/v4l2/v4l2_camera_proxy.cpp | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> > index 45822feff317..67b2c50c0f7e 100644
> > --- a/src/v4l2/v4l2_camera_proxy.cpp
> > +++ b/src/v4l2/v4l2_camera_proxy.cpp
> > @@ -234,7 +234,7 @@ void V4L2CameraProxy::updateBuffers()
> >                                                       });
> >                       buf.field = V4L2_FIELD_NONE;
> >                       buf.timestamp.tv_sec = fmd.timestamp / 1000000000;
> > -                     buf.timestamp.tv_usec = fmd.timestamp % 1000000;
> > +                     buf.timestamp.tv_usec = fmd.timestamp / 1000 % 1000000;
> 
> I'd have written
> 
>                         buf.timestamp.tv_usec = (fmd.timestamp / 1000) % 1000000;

aha, normally I expect you to suggest removing brackets ;-) But I can
add these.

> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> either way.
> 

Thanks, will collect tags, fix the minors and push.

> >                       buf.sequence = fmd.sequence;
> >  
> >                       buf.flags |= V4L2_BUF_FLAG_DONE;
> 
> -- 
> Regards,
> 
> Laurent Pinchart