staging: gma500: Skip bogus LVDS VBT mode and check for LVDS before adding backlight

On the Fit-PC2 the VBT reports an invalid fixed panel mode for LVDS, this gets
in the way for SDVO. This patch makes VBT parsing skip the invalid mode. When
there is no LVDS output the backlight support crashes so the patch also checks
for this before enabling it.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/gma500/psb_drv.c

@@ -542,6 +542,8 @@ static int psb_driver_load(struct drm_device *dev, unsigned long chipset)
 	unsigned long irqflags;
 	int ret = -ENOMEM;
 	uint32_t tt_pages;
+	struct drm_connector *connector;
+	struct psb_intel_output *psb_intel_output;
 
 	dev_priv = kzalloc(sizeof(*dev_priv), GFP_KERNEL);
 	if (dev_priv == NULL)
@@ -663,7 +665,18 @@ static int psb_driver_load(struct drm_device *dev, unsigned long chipset)
 		drm_kms_helper_poll_init(dev);
 	}
 
-	ret = psb_backlight_init(dev);
+	/* Only add backlight support if we have LVDS output */
+	list_for_each_entry(connector, &dev->mode_config.connector_list,
+			    head) {
+		psb_intel_output = to_psb_intel_output(connector);
+
+		switch (psb_intel_output->type) {
+		case INTEL_OUTPUT_LVDS:
+			ret = psb_backlight_init(dev);
+			break;
+		}
+	}
+
 	if (ret)
 		return ret;
 #if 0

drivers/staging/gma500/psb_intel_bios.c

@@ -154,10 +154,15 @@ static void parse_lfp_panel_data(struct drm_psb_private *dev_priv,
 
 	fill_detail_timing_data(panel_fixed_mode, dvo_timing);
 
-	dev_priv->lfp_lvds_vbt_mode = panel_fixed_mode;
-
-	DRM_DEBUG("Found panel mode in BIOS VBT tables:\n");
-	drm_mode_debug_printmodeline(panel_fixed_mode);
+	if (panel_fixed_mode->htotal > 0 && panel_fixed_mode->vtotal > 0) {
+		dev_priv->lfp_lvds_vbt_mode = panel_fixed_mode;
+		DRM_DEBUG("Found panel mode in BIOS VBT tables:\n");
+		drm_mode_debug_printmodeline(panel_fixed_mode);
+	} else {
+		DRM_DEBUG("Ignoring bogus LVDS VBT mode.\n");
+		dev_priv->lvds_vbt = 0;
+		kfree(panel_fixed_mode);
+	}
 
 	return;
 }