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

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=1021442098ee9328fdd4d113d63a3a7f2f40c37b
Commit:     1021442098ee9328fdd4d113d63a3a7f2f40c37b
Parent:     7c6c2652bab9601883ed579071aa56ab52a28ea6
Author:     Daniel Vetter <daniel.vetter at ffwll.ch>
AuthorDate: Mon Nov 18 07:38:16 2013 +0100
Committer:  Daniel Vetter <daniel.vetter at ffwll.ch>
CommitDate: Tue Nov 19 16:59:39 2013 +0100

    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 at 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 at vger.kernel.org
    Tested-by: Gökçen Eraslan <gokcen.eraslan at gmail.com>
    Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
    Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/intel_ddi.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 1591576..330077b 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)