drm/i915: Return SDVO LVDS VBT mode if no EDID modes are detected.

Some new SDVO LVDS hardware doesn't have DDC available, and this should
fix the display on it.

Signed-off-by: Ma Ling <ling.ma@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 9913651c1e17..f79ebf4de63c 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -69,6 +69,10 @@ struct intel_sdvo_priv {
          * This is set if we treat the device as HDMI, instead of DVI.
          */
         bool is_hdmi;
+        /**
+         * This is set if we detect output of sdvo device as LVDS.
+         */
+        bool is_lvds;
 
         /**
          * Returned SDTV resolutions allowed for the current format, if the
@@ -1543,6 +1547,37 @@ static void intel_sdvo_get_tv_modes(struct drm_connector *connector)
                 }
 }
 
+static void intel_sdvo_get_lvds_modes(struct drm_connector *connector)
+{
+        struct intel_output *intel_output = to_intel_output(connector);
+        struct intel_sdvo_priv *sdvo_priv = intel_output->dev_priv;
+        struct drm_i915_private *dev_priv = connector->dev->dev_private;
+
+        /*
+         * Attempt to get the mode list from DDC.
+         * Assume that the preferred modes are
+         * arranged in priority order.
+         */
+        /* set the bus switch and get the modes */
+        intel_sdvo_set_control_bus_switch(intel_output, sdvo_priv->ddc_bus);
+        intel_ddc_get_modes(intel_output);
+        if (list_empty(&connector->probed_modes) == false)
+                return;
+
+        /* Fetch modes from VBT */
+        if (dev_priv->sdvo_lvds_vbt_mode != NULL) {
+                struct drm_display_mode *newmode;
+                newmode = drm_mode_duplicate(connector->dev,
+                                             dev_priv->sdvo_lvds_vbt_mode);
+                if (newmode != NULL) {
+                        /* Guarantee the mode is preferred */
+                        newmode->type = (DRM_MODE_TYPE_PREFERRED |
+                                         DRM_MODE_TYPE_DRIVER);
+                        drm_mode_probed_add(connector, newmode);
+                }
+        }
+}
+
 static int intel_sdvo_get_modes(struct drm_connector *connector)
 {
         struct intel_output *output = to_intel_output(connector);
@@ -1550,6 +1585,8 @@ static int intel_sdvo_get_modes(struct drm_connector *connector)
 
         if (sdvo_priv->is_tv)
                 intel_sdvo_get_tv_modes(connector);
+        else if (sdvo_priv->is_lvds == true)
+                intel_sdvo_get_lvds_modes(connector);
         else
                 intel_sdvo_get_ddc_modes(connector);
 
@@ -1720,6 +1757,8 @@ bool intel_sdvo_init(struct drm_device *dev, int output_device)
                 }
         }
 
+        /* In defaut case sdvo lvds is false */
+        sdvo_priv->is_lvds = false;
         intel_sdvo_get_capabilities(intel_output, &sdvo_priv->caps);
 
         if (sdvo_priv->caps.output_flags &
@@ -1773,6 +1812,7 @@ bool intel_sdvo_init(struct drm_device *dev, int output_device)
                 connector->display_info.subpixel_order = SubPixelHorizontalRGB;
                 encoder_type = DRM_MODE_ENCODER_LVDS;
                 connector_type = DRM_MODE_CONNECTOR_LVDS;
+                sdvo_priv->is_lvds = true;
         }
         else if (sdvo_priv->caps.output_flags & SDVO_OUTPUT_LVDS1)
         {
@@ -1780,6 +1820,7 @@ bool intel_sdvo_init(struct drm_device *dev, int output_device)
                 connector->display_info.subpixel_order = SubPixelHorizontalRGB;
                 encoder_type = DRM_MODE_ENCODER_LVDS;
                 connector_type = DRM_MODE_CONNECTOR_LVDS;
+                sdvo_priv->is_lvds = true;
         }
         else
         {