From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [RFC 4/4] drm: add support for raw monotonic vblank timestamps
Date: Sun, 7 Oct 2012 22:33:46 +0200
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To: Imre Deak <imre.deak@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Rob Clark <rob.clark@linaro.org>
List-Id: intel-gfx@lists.freedesktop.org

On Sat, Oct 06, 2012 at 03:49:16AM +0300, Imre Deak wrote:
> On Fri, 2012-10-05 at 18:09 -0600, Rob Clark wrote:
> > 
> > 	/* Called before vblank count and timestamps have
> > 	 * been updated for the vblank interval of flip
> > 	 * completion? Need to increment vblank count and
> > 	 * add one videorefresh duration to returned timestamp
> > 	 * to account for this. We assume this happened if we
> > 	 * get called over 0.9 frame durations after the last
> > 	 * timestamped vblank.
> > 	 *
> > 	 * This calculation can not be used with vrefresh rates
> > 	 * below 5Hz (10Hz to be on the safe side) without
> > 	 * promoting to 64 integers.
> > 	 */
> > 	if (10 * (timeval_to_ns(&tnow) - timeval_to_ns(&tvbl)) >
> > 	    9 * crtc->framedur_ns) {
> > 		event->event.sequence++;
> > 		tvbl = ns_to_timeval(timeval_to_ns(&tvbl) +
> > 				     crtc->framedur_ns);
> > 	}
> 
> This has been recently removed by danvet's "drm/i915: don't frob the
> vblank ts in finish_page_flip", though not yet committed, so we can do
> away with it here too.

Yeah, I'd prefer if the common code doesn't have such hackes - this bit
here papered over some bugs in our driver code, but only partially
successfully ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch