1 files changed, 52 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index fcab9dee93da..a86af0d24fd3 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -35,6 +35,7 @@
 #include "i915_drv.h"
 #include "intel_dp.h"
 
+
 #define DP_LINK_STATUS_SIZE     6
 #define DP_LINK_CHECK_TIMEOUT   (10 * 1000)
 
@@ -1228,7 +1229,53 @@ intel_dp_hot_plug(struct intel_output *intel_output)
         if (dp_priv->dpms_mode == DRM_MODE_DPMS_ON)
                 intel_dp_check_link_status(intel_output);
 }
-
+/*
+ * Enumerate the child dev array parsed from VBT to check whether
+ * the given DP is present.
+ * If it is present, return 1.
+ * If it is not present, return false.
+ * If no child dev is parsed from VBT, it is assumed that the given
+ * DP is present.
+ */
+int dp_is_present_in_vbt(struct drm_device *dev, int dp_reg)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        struct child_device_config *p_child;
+        int i, dp_port, ret;
+
+        if (!dev_priv->child_dev_num)
+                return 1;
+
+        dp_port = 0;
+        if (dp_reg == DP_B || PCH_DP_B)
+                dp_port = PORT_IDPB;
+        else if (dp_reg == DP_C || PCH_DP_C)
+                dp_port = PORT_IDPC;
+        else if (dp_reg == DP_D || PCH_DP_D)
+                dp_port = PORT_IDPD;
+
+        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 DP, continue.
+                 */
+                if (p_child->device_type != DEVICE_TYPE_DP &&
+                        p_child->device_type != DEVICE_TYPE_eDP)
+                        continue;
+                /* Find the eDP port */
+                if (dp_reg == DP_A && p_child->device_type == DEVICE_TYPE_eDP) {
+                        ret = 1;
+                        break;
+                }
+                /* Find the DP port */
+                if (p_child->dvo_port == dp_port) {
+                        ret = 1;
+                        break;
+                }
+        }
+        return ret;
+}
 void
 intel_dp_init(struct drm_device *dev, int output_reg)
 {
@@ -1238,6 +1285,10 @@ intel_dp_init(struct drm_device *dev, int output_reg)
         struct intel_dp_priv *dp_priv;
         const char *name = NULL;
 
+        if (!dp_is_present_in_vbt(dev, output_reg)) {
+                DRM_DEBUG_KMS("DP is not present. Ignore it\n");
+                return;
+        }
         intel_output = kcalloc(sizeof(struct intel_output) + 
                                sizeof(struct intel_dp_priv), 1, GFP_KERNEL);
         if (!intel_output)