drm/edid: add quirk for BPC in Samsung NP700G7A-S01PL notebook

This bug in EDID was exposed by:

commit eccea79
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Mon Mar 26 15:12:54 2012 -0400

    drm/radeon/kms: improve bpc handling (v2)

Which resulted in kind of regression in 3.5. This fixes
https://bugs.freedesktop.org/show_bug.cgi?id=70934

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_edid.c

@@ -68,6 +68,8 @@
 #define EDID_QUIRK_DETAILED_SYNC_PP		(1 << 6)
 /* Force reduced-blanking timings for detailed modes */
 #define EDID_QUIRK_FORCE_REDUCED_BLANKING	(1 << 7)
+/* Force 8bpc */
+#define EDID_QUIRK_FORCE_8BPC			(1 << 8)
 
 struct detailed_mode_closure {
 	struct drm_connector *connector;
@@ -128,6 +130,9 @@ static struct edid_quirk {
 
 	/* Medion MD 30217 PG */
 	{ "MED", 0x7b8, EDID_QUIRK_PREFER_LARGE_75 },
+
+	/* Panel in Samsung NP700G7A-S01PL notebook reports 6bpc */
+	{ "SEC", 0xd033, EDID_QUIRK_FORCE_8BPC },
 };
 
 /*
@@ -3435,6 +3440,9 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
 
 	drm_add_display_info(edid, &connector->display_info);
 
+	if (quirks & EDID_QUIRK_FORCE_8BPC)
+		connector->display_info.bpc = 8;
+
 	return num_modes;
 }
 EXPORT_SYMBOL(drm_add_edid_modes);