[PATCH weston 2/2] compositor-drm: Fix inconsistency in finish frame timestamps

[Pekka Paalanen]

On Thu, 14 Feb 2013 11:51:15 -0500
Kristian Høgsberg <hoegsberg at gmail.com> wrote:

> On Wed, Feb 13, 2013 at 04:06:38PM +0200, Ander Conselvan de Oliveira wrote:
> > The page flip event timestamps comes from the monotonic clock, while
> > idle_repaint() gets the time with gettimeofday(). That leads to
> > inconsistent timestamps on the frame callbacks.
> > 
> > Fix this by making the drm backend page flip to the current buffer and
> > call weston_output_finish_frame() with the page flip event timestamp,
> > instead of using gettimeofday().
> 
> Yup, this looks right, but I think we need to require that all
> backends provide a start_repaint_loop function.  Only the backend
> knows what kind of timestamp comes back in finish_frame, so we can't
> assume gttimeofday() as a fallback.  compositor-wayland.c uses the
> frame callback timestamp, for example, and if the host weston is
> running on KMS, that's a monotonic timestamp from the underlying
> pageflip event.

Hi,

while you are making the timestamps consistent, could also make them,
err... correct?

I think the current code in weston_output_repaint() is sending out the
frame callbacks at the moment the rendering has been started, not when
when it has hit the screen. Do you agree?


Thanks,
pq