From: "Keith Packard" <keithp@keithp.com>
To: "drivers, Intel" <Intel-gfx@lists.freedesktop.org>,
dri-devel@lists.freedesktop.org
Subject: vblank_count count jumps backwards and then forwards across system suspend
Date: Mon, 11 Nov 2013 16:23:26 -0800 [thread overview]
Message-ID: <86ppq6bh8h.fsf@miki.keithp.com> (raw)
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I'm getting some weird results when using vblank_count on my Ivybridge
machine across suspend/resume.
With glxgears running, I suspend the machine. At resume, I see
vblank_count temporarily jump back by a fairly large amount (usually
between 10000 and 20000 frames). After a short while, it recovers and
jumps back to something that looks like it's back on track with values
From before the suspend.
I thought at first that the value was just getting set back and left
there, but after working around that kind of bug, I discovered that it
only stayed on the wrong sequence for a short while (looks like about
20ms) and then jumps back to the previous sequence. I hacked up the
vblank code to show where the errors occurred, and here's what I got
(the logged MSC values are bogus, but the sequence of events is
correct):
Vblank goes haywire here:
[ 30348.438] expect msc near 4294871473 got msc 4294860521
[ 30348.441] (II) intel(0): EDID vendor "APP", prod id 40178
[ 30348.442] (II) intel(0): Printing DDC gathered Modelines:
[ 30348.442] (II) intel(0): Modeline "1366x768"x0.0 72.00 1366 1380 1436 1500 768 769 772 800 -hsync -vsync (48.0 kHz eP)
Vblank recovers here:
[ 30348.458] expect msc near 4294849570 got msc 4294860522
--
keith.packard@intel.com
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