linux-kernel - Re: [Intel-gfx] [PATCH 2/4] drm/i915: Leave LVDS registers unlocked

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Date:	Mon, 8 Aug 2011 13:25:31 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Keith Packard <keithp@...thp.com>
Cc:	Dave Airlie <airlied@...hat.com>, intel-gfx@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 2/4] drm/i915: Leave LVDS registers unlocked

On Mon, 08 Aug 2011 13:24:12 -0700
Keith Packard <keithp@...thp.com> wrote:

> On Mon, 8 Aug 2011 13:01:28 -0700, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> > On Mon, 08 Aug 2011 12:53:31 -0700
> > Keith Packard <keithp@...thp.com> wrote:
> > 
> > > On Mon, 8 Aug 2011 11:49:54 -0700, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> > > 
> > > > Yep, it's safe and possible to do on pre-PCH as well.  For panel
> > > > fitting we do need to do an actual power cycle when going from
> > > > non-native back to native iirc, but we can still leave them unlocked so
> > > > we don't have to worry about the lock/unlock sequence everywhere.
> > > 
> > > Hidden in the unlock patch was a call to intel_lvds_disable from
> > > intel_lvds_prepare -- that *always* turns off the LVDS for mode
> > > setting. Do we care enough about LVDS mode setting performance that we
> > > should try leave the optimization in place that doesn't turn off the
> > > backlight when switching between modes?
> > 
> > We hate flicker right?  But generally yes it's safer to just turn it
> > off all the time.
> 
> I'll leave the optimization in place then; it's been there for a while
> so at least it shouldn't cause any regressions.
> 
> How about this? Has the advantage of not lying in the commit message
> anymore.
> 
> From 092719152aa5a235d6678798a34dc784d5cec2ad Mon Sep 17 00:00:00 2001
> From: Keith Packard <keithp@...thp.com>
> Date: Sat, 6 Aug 2011 10:33:12 -0700
> Subject: [PATCH 2/5] drm/i915: Leave LVDS registers unlocked
> 
> There's no reason to relock them; it just makes operations more
> complex. This fixes DPMS where the panel registers were locked making
> the disable not work.
> 
> Signed-off-by: Keith Packard <keithp@...thp.com>

Yeah looks like a nice improvement.

Reviewed-by: Jesse Barnes <jbarnes@...tuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center
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