drm/i915: Replicate BIOS eDP bpp clamping hack for hsw

Haswell's DDI encoders have their own ->get_config callback and in

commit c6cd2ee2d59111a07cd9199564c9bdcb2d11e5cf
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Mon Oct 21 10:52:07 2013 +0300

    drm/i915/dp: workaround BIOS eDP bpp clamping issue

we've forgotten to replicate this hack. So let's do it that.

Note for backporters: The above commit and all it's depencies need to
be backported first.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71049
Cc: stable@vger.kernel.org
Tested-by: Gökçen Eraslan <gokcen.eraslan@gmail.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 1591576a6101..330077bcd0bd 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1406,6 +1406,26 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
         default:
                 break;
         }
+
+        if (encoder->type == INTEL_OUTPUT_EDP && dev_priv->vbt.edp_bpp &&
+            pipe_config->pipe_bpp > dev_priv->vbt.edp_bpp) {
+                /*
+                 * This is a big fat ugly hack.
+                 *
+                 * Some machines in UEFI boot mode provide us a VBT that has 18
+                 * bpp and 1.62 GHz link bandwidth for eDP, which for reasons
+                 * unknown we fail to light up. Yet the same BIOS boots up with
+                 * 24 bpp and 2.7 GHz link. Use the same bpp as the BIOS uses as
+                 * max, not what it tells us to use.
+                 *
+                 * Note: This will still be broken if the eDP panel is not lit
+                 * up by the BIOS, and thus we can't get the mode at module
+                 * load.
+                 */
+                DRM_DEBUG_KMS("pipe has %d bpp for eDP panel, overriding BIOS-provided max %d bpp\n",
+                              pipe_config->pipe_bpp, dev_priv->vbt.edp_bpp);
+                dev_priv->vbt.edp_bpp = pipe_config->pipe_bpp;
+        }
 }
 
 static void intel_ddi_destroy(struct drm_encoder *encoder)