[Intel-gfx] [PATCH] drm/i915: Boost GPU clocks if we miss the pageflip's vblank

[Chris Wilson]

Quoting Szwichtenberg, Radoslaw (2017-08-18 09:50:35)
> On Fri, 2017-08-18 at 08:54 +0100, Chris Wilson wrote:
> > Quoting Chris Wilson (2017-08-17 13:37:06)
> > > If we miss the current vblank because the gpu was busy, that may cause a
> > > jitter as the frame rate temporarily drops. We try to limit the impact
> > > of this by then boosting the GPU clock to deliver the frame as quickly
> > > as possible. Originally done in commit 6ad790c0f5ac ("drm/i915: Boost GPU
> > > frequency if we detect outstanding pageflips") but was never forward
> > > ported to atomic and finally dropped in commit fd3a40242e87 ("drm/i915:
> > > Rip out legacy page_flip completion/irq handling").
> > 
> >  
> > > References: https://bugs.freedesktop.org/show_bug.cgi?id=102199
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102199
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Cc: Daniel Vetter <daniel.vetter at intel.com>
> > 
> > Tested-by: Lyude Paul <lyude at redhat.com>
> Reviewed-by: Radoslaw Szwichtenberg <radoslaw.szwichtenberg at intel.com>

Added the blurb to explain itself better and pushed to paper over the
miserable UX performance.
-Chris