drm/i915: Don't set up the LVDS if it isn't in the BIOS device table.

We not only check the device type, but also check the addin_offset. If the
addin_offset is zero, it won't be initialized.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
[anholt: hand-applied due to conflicts]

1 files changed, 44 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index ab48edde4c9f..7fec70145a3d 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -968,6 +968,46 @@ static void intel_find_lvds_downclock(struct drm_device *dev,
         return;
 }
 
+/*
+ * Enumerate the child dev array parsed from VBT to check whether
+ * the LVDS is present.
+ * If it is present, return 1.
+ * If it is not present, return false.
+ * If no child dev is parsed from VBT, it assumes that the LVDS is present.
+ * Note: The addin_offset should also be checked for LVDS panel.
+ * Only when it is non-zero, it is assumed that it is present.
+ */
+int lvds_is_present_in_vbt(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        struct child_device_config *p_child;
+        int i, ret;
+
+        if (!dev_priv->child_dev_num)
+                return 1;
+
+        ret = 0;
+        for (i = 0; i < dev_priv->child_dev_num; i++) {
+                p_child = dev_priv->child_dev + i;
+                /*
+                 * If the device type is not LFP, continue.
+                 * If the device type is 0x22, it is also regarded as LFP.
+                 */
+                if (p_child->device_type != DEVICE_TYPE_INT_LFP &&
+                        p_child->device_type != DEVICE_TYPE_LFP)
+                        continue;
+
+                /* The addin_offset should be checked. Only when it is
+                 * non-zero, it is regarded as present.
+                 */
+                if (p_child->addin_offset) {
+                        ret = 1;
+                        break;
+                }
+        }
+        return ret;
+}
+
 /**
  * intel_lvds_init - setup LVDS connectors on this device
  * @dev: drm device
@@ -991,6 +1031,10 @@ void intel_lvds_init(struct drm_device *dev)
         if (dmi_check_system(intel_no_lvds))
                 return;
 
+        if (!lvds_is_present_in_vbt(dev)) {
+                DRM_DEBUG_KMS("LVDS is not present in VBT\n");
+                return;
+        }
         /* Assume that any device without an ACPI LID device also doesn't
          * have an integrated LVDS.  We would be better off parsing the BIOS
          * to get a reliable indicator, but that code isn't written yet.