drm/i915: Override SDVO panel type in VBT

Judging by comments in the BIOS, if the SDVO LVDS option h40 is enabled,
then we are supposed to query the real panel type via Int15. We don't do
this and so for the Sony Vaio VGC-JS210J which has otherwise default
values, we choose the wrong mode.

This patch adds a driver option, i915.vbt_sdvo_panel_type, which can be
used to override the value in the VBT.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=33691
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.c

@@ -52,6 +52,9 @@ module_param_named(lvds_downclock, i915_lvds_downclock, int, 0400);
 unsigned int i915_panel_use_ssc = 1;
 module_param_named(lvds_use_ssc, i915_panel_use_ssc, int, 0600);
 
+int i915_vbt_sdvo_panel_type = -1;
+module_param_named(vbt_sdvo_panel_type, i915_vbt_sdvo_panel_type, int, 0600);
+
 static bool i915_try_reset = true;
 module_param_named(reset, i915_try_reset, bool, 0600);
 

drivers/gpu/drm/i915/i915_drv.h

@@ -962,6 +962,7 @@ extern unsigned int i915_fbpercrtc;
 extern unsigned int i915_powersave;
 extern unsigned int i915_lvds_downclock;
 extern unsigned int i915_panel_use_ssc;
+extern int i915_vbt_sdvo_panel_type;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);
 extern int i915_resume(struct drm_device *dev);

drivers/gpu/drm/i915/intel_bios.c

@@ -226,29 +226,35 @@ static void
 parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
 		      struct bdb_header *bdb)
 {
-	struct bdb_sdvo_lvds_options *sdvo_lvds_options;
 	struct lvds_dvo_timing *dvo_timing;
 	struct drm_display_mode *panel_fixed_mode;
+	int index;
 
-	sdvo_lvds_options = find_section(bdb, BDB_SDVO_LVDS_OPTIONS);
-	if (!sdvo_lvds_options)
-		return;
+	index = i915_vbt_sdvo_panel_type;
+	if (index == -1) {
+		struct bdb_sdvo_lvds_options *sdvo_lvds_options;
+
+		sdvo_lvds_options = find_section(bdb, BDB_SDVO_LVDS_OPTIONS);
+		if (!sdvo_lvds_options)
+			return;
+
+		index = sdvo_lvds_options->panel_type;
+	}
 
 	dvo_timing = find_section(bdb, BDB_SDVO_PANEL_DTDS);
 	if (!dvo_timing)
 		return;
 
 	panel_fixed_mode = kzalloc(sizeof(*panel_fixed_mode), GFP_KERNEL);
-
 	if (!panel_fixed_mode)
 		return;
 
-	fill_detail_timing_data(panel_fixed_mode,
-			dvo_timing + sdvo_lvds_options->panel_type);
+	fill_detail_timing_data(panel_fixed_mode, dvo_timing + index);
 
 	dev_priv->sdvo_lvds_vbt_mode = panel_fixed_mode;
 
-	return;
+	DRM_DEBUG_KMS("Found SDVO panel mode in BIOS VBT tables:\n");
+	drm_mode_debug_printmodeline(panel_fixed_mode);
 }
 
 static int intel_bios_ssc_frequency(struct drm_device *dev,