[PATCH] drm/i915: quirk away broken OpRegion VBT

[Daniel Vetter <daniel.vetter@ffwll.ch>]

Somehow the BIOS manages to screw things up when copying the VBT
around, because the one we scrap from the VBIOS rom actually works.

Cc: stable@kernel.org
Tested-by: Markus Heinz <markus.heinz@uni-dortmund.de>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=28812
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/intel_bios.c |   23 ++++++++++++++++++++++-
 1 files changed, 22 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index e4317da..d6ffdbd 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -24,6 +24,7 @@
  *    Eric Anholt <eric@anholt.net>
  *
  */
+#include <linux/dmi.h>
 #include <drm/drm_dp_helper.h>
 #include "drmP.h"
 #include "drm.h"
@@ -662,6 +663,26 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 	dev_priv->edp.bpp = 18;
 }
 
+static int __init intel_no_opregion_vbt_callback(const struct dmi_system_id *id)
+{
+	DRM_DEBUG_KMS("Falling back to manually reading VBT from "
+		      "VBIOS ROM for %s\n",
+		      id->ident);
+	return 1;
+}
+
+static const struct dmi_system_id intel_no_opregion_vbt[] = {
+	{
+		.callback = intel_no_opregion_vbt_callback,
+		.ident = "ThinkCentre A57",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "97027RG"),
+		},
+	},
+	{ }
+};
+
 /**
  * intel_parse_bios - find VBT and initialize settings from the BIOS
  * @dev: DRM device
@@ -682,7 +703,7 @@ intel_parse_bios(struct drm_device *dev)
 	init_vbt_defaults(dev_priv);
 
 	/* XXX Should this validation be moved to intel_opregion.c? */
-	if (dev_priv->opregion.vbt) {
+	if (!dmi_check_system(intel_no_opregion_vbt) && dev_priv->opregion.vbt) {
 		struct vbt_header *vbt = dev_priv->opregion.vbt;
 		if (memcmp(vbt->signature, "$VBT", 4) == 0) {
 			DRM_DEBUG_KMS("Using VBT from OpRegion: %20s\n",
-- 
1.7.9.1