[Intel-gfx] [PATCH 5/5] drm/i915: Allow vblank interrupts during modeset and eliminate some vblank races

[Ville Syrjälä]

On Mon, Feb 24, 2014 at 12:48:55PM +0900, Michel Dänzer wrote:
> On Fre, 2014-02-21 at 21:03 +0200, ville.syrjala at linux.intel.com wrote:
> > 
> > We can kill of the drm_vblank_{pre,post}_modeset() calls since those are
> > there simply to make drm_vblank_get() fail during a modeset.
> 
> Actually, their original purpose was to keep the DRM vblank counter
> consistent across modesets, assuming the modeset resets the hardware
> vblank counter.

I see. Well, actually I really don't. The code is too funky for me to
tell what it actually ends up doing. The obvious way would be to
resample the hardware counter at drm_vblank_post_modeset(), which the
code certainly doesn't do. But maybe it did something sensible in the
past.

-- 
Ville Syrjälä
Intel OTC