[Intel-gfx] [PATCH 1/2] drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

[Daniel Vetter]

On Tue, Mar 20, 2012 at 01:07:05PM +0100, Takashi Iwai wrote:
> Currently i915 driver checks [PCH_]LVDS register bits to decide
> whether to set up the dual-link or the single-link mode.  This relies
> implicitly on that BIOS initializes the register properly at boot.
> However, BIOS doesn't initialize it always.  When the machine is
> booted with the closed lid, BIOS skips the LVDS reg initialization.
> This ends up in blank output on a machine with a dual-link LVDS when
> you open the lid after the boot.
> 
> This patch adds a workaround for that problem by checking the initial
> LVDS register value in VBT.
> 
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
> Reviewed-by: Adam Jackson <ajax at redhat.com>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=37742

Not tested by the reporter, but sounds exactly like the issue this patch
here tries to fix.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48