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

Daniel Vetter daniel at ffwll.ch
Tue Mar 20 11:01:22 CET 2012

On Mon, Mar 19, 2012 at 12:07:36PM +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>

If I understand Keith correctly he would like this to only get used when
the lid is closed and the panel is off. But I don't see that mention in
you change log nor can I find how it works in the code. Has this been lost
or am I confused?

Thanks, Daniel
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48

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