From: Jani Nikula <jani.nikula@intel.com>
Date: Mon, 9 Jun 2014 15:24:34 +0000 (+0300)
Subject: drm/i915: set backlight duty cycle after backlight enable for gen4
X-Git-Tag: omap-for-v3.16/fixes-rc4~80^2^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2e7eeeb59a92d09144fdb7d2dc1af77a10a7945b;p=pandora-kernel.git

drm/i915: set backlight duty cycle after backlight enable for gen4

For reasons I can't claim to fully understand gen4 seems to require
backlight duty cycle setting after the backlight has been enabled, or
else black screen follows. I don't have documentation for the correct
sequence on gen4 either. Confirmed on Dell Latitude D630 and MacBook4,1.

This fixes a regression introduced by
commit b35684b8fa94e04f55fd38bf672b737741d2f9e2
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Thu Nov 14 12:13:41 2013 +0200

    drm/i915: do full backlight setup at enable time

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=75791
Reported-and-tested-by: mcy@lm7.fr
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=79423
Reported-and-tested-by: Marc Milgram <mmilgram@redhat.com>
Cc: Stable <stable@vger.kernel.org> # 3.14+
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---

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