From: Adam Jackson <ajax@redhat.com>
Date: Tue, 13 Dec 2011 23:41:00 +0000 (-0800)
Subject: drm/i915/dp: Dither down to 6bpc if it makes the mode fit
X-Git-Tag: v3.2-rc6~5^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3b5c78a35cf7511c15e09a9b0ffab290a42d9bcf;p=pandora-kernel.git

drm/i915/dp: Dither down to 6bpc if it makes the mode fit

Some active adaptors (VGA usually) only have two lanes at 2.7GHz.
That's a maximum pixel clock of 144MHz at 8bpc, but 192MHz at 6bpc.

Fixes Asus UX31 panel being black at startup due to no valid modes since
dc22ee6fc18ce0f15424e753e8473c306ece95c1.

v2: Rebased to current code, resulting in the fix applying to EDP panels as
    well.  Also changed from spatio-temporal to just spatial dithering on
    pre-ironlake, to be conssitent (and less visual flicker)

Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Tested-by: Eric Anholt <eric@anholt.net>
Tested-by: Dirk Hohndel <hohndel@infradead.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
---

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