On Tue, May 22, 2012 at 08:46:06PM +0100, Chris Wilson wrote: > On Tue, 22 May 2012 21:41:25 +0200, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > > Otherwise the hw will get confused and result in a black screen. > > > > This regression has been most likely introduce in > > > > commit 974b93315b2213b74a42a87e8a9d4fc8c0dbe90c > > Author: Chris Wilson <chris at chris-wilson.co.uk> > > Date: Sun Sep 5 00:44:20 2010 +0100 > > > > drm/i915/tv: Poll for DAC state change > > > > That commit replace the first msleep(20) with a busy-loop, but failed > > to keep the 2nd msleep around. Later on we've replaced all these > > msleep(20) by proper vblanks. > > > > For reference also see the commit in xf86-video-intel: > > > > commit 1142be53eb8d2ee8a9b60ace5d49f0ba27332275 > > Author: Jesse Barnes <jbarnes at hobbes.lan> > > Date: Mon Jun 9 08:52:59 2008 -0700 > > > > Fix TV programming: add vblank wait after TV_CTL writes > > > > Fxies FDO bug #14000; we need to wait for vblank after > > writing TV_CTL or following "DPMS on" calls may not actually enable the output. > > > > v2: As suggested by Chris Wilson, add a small comment to ensure that > > no one accidentally removes this vblank wait again - there really > > seems to be no sane explanation for why we need it, but it is > > required. > > > > Launchpad: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/763688 > > Reported-and-Tested-by: Robert Lowery <rglowery at exemail.com.au> > > Cc: Rodrigo Vivi <rodrigo.vivi at gmail.com> > > Cc: stable at kernel.org > Cc: stable at vger.kernel.org > > Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch> > Acked-by: Chris Wilson <chris at chris-wilson.co.uk> I've picked this one up for -fixes, thanks for the comments. -Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
