On Wed, Jun 13, 2012 at 09:36:00AM -0500, Seth Forshee wrote: > When I boot my Thinkpad T410 in a docking station with the lid closed, > the lvds panel remains blank even when this output is active. This > happens up to and including 3.5-rc2. > > I've determined that this happens because lvds isn't being initialized > by the bios when I boot this way, and booting with lvds_channel_mode=2 > fixes the issue. I see that there's logic in is_dual_link_lvds() > intended to detect this situation, but it's failing because the T410 has > the LVDS_PIPEB_SELECT bit set. The simple patch below fixes my machine > by masking off this bit when determining whether or not lvds was > initialized by the bios. > > I'm not sure though whether or not it's correct to expect that this bit > might be set when lvds hasn't been initialized. The alternative seems to > be quirking this machine as is done for some Macbooks. What is the > correct solution? Patch looks correct, but can you please change the mask from PIPEB to the already exsting LVDS_PIPE_MASK? This way it's clearer what's going on. Thanks, Daniel > > Thanks, > Seth > > > From 250904ac95cda7630cdd8339724e3c8feceeb586 Mon Sep 17 00:00:00 2001 > From: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > Date: Tue, 12 Jun 2012 16:52:14 -0500 > Subject: [PATCH] drm/i915: ignore LVDS_PIPEB_SELECT when checking for LVDS > register initialization > > The Lenovo Thinkpad T410 has this bit set in the LVDS register when > booted with the lid closed, even though the LVDS hasn't really been > initialized. Ignore this bit so that the VBT value will be used instead. > > Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_display.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c > index e0aa064..f81f249 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -434,7 +434,7 @@ static bool is_dual_link_lvds(struct drm_i915_private *dev_priv, > * register is uninitialized. > */ > val = I915_READ(reg); > - if (!(val & ~LVDS_DETECTED)) > + if (!(val & ~(LVDS_PIPEB_SELECT | LVDS_DETECTED))) > val = dev_priv->bios_lvds_val; > dev_priv->lvds_val = val; > } > -- Daniel Vetter Mail: daniel@xxxxxxxx Mobile: +41 (0)79 365 57 48 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
