From 8a9e7e1715b42ba77cb2a08be142c967a71ef93b Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Wed, 25 Apr 2012 14:37:27 +0100
Subject: [PATCH] --- yaml --- r: 307103 b: refs/heads/master c:
 1b2db4cee5433e089533f81fea6721c1b653703c h: refs/heads/master i:   307101:
 ecb354bfcd6400b2047be68ff9b3079e175b5a52   307099:
 3e5b70962605b1f5177c1bfc8a15da71d21118b7   307095:
 000082471adddc8bd548b71c6e37a61423db721b   307087:
 3a6dd9bc81e9a50c5959d87423c8bee1bc0ab59e   307071:
 a37fffbcb59d9efffee4fd0c900aba1dc25bd080 v: v3

---
 [refs]                                        |  2 +-
 trunk/drivers/gpu/drm/gma500/cdv_intel_lvds.c | 57 +++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index f44e72ab55de..2be94b8870d7 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1fb28e9e737e26a0d2ee59f211ff400dc448d7e5
+refs/heads/master: 1b2db4cee5433e089533f81fea6721c1b653703c
diff --git a/trunk/drivers/gpu/drm/gma500/cdv_intel_lvds.c b/trunk/drivers/gpu/drm/gma500/cdv_intel_lvds.c
index 8359c1a3f45f..c87b179eadfd 100644
--- a/trunk/drivers/gpu/drm/gma500/cdv_intel_lvds.c
+++ b/trunk/drivers/gpu/drm/gma500/cdv_intel_lvds.c
@@ -556,6 +556,56 @@ const struct drm_encoder_funcs cdv_intel_lvds_enc_funcs = {
 	.destroy = cdv_intel_lvds_enc_destroy,
 };
 
+/*
+ * 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.
+ */
+static bool lvds_is_present_in_vbt(struct drm_device *dev,
+				   u8 *i2c_pin)
+{
+	struct drm_psb_private *dev_priv = dev->dev_private;
+	int i;
+
+	if (!dev_priv->child_dev_num)
+		return true;
+
+	for (i = 0; i < dev_priv->child_dev_num; i++) {
+		struct child_device_config *child = dev_priv->child_dev + i;
+
+		/* If the device type is not LFP, continue.
+		 * We have to check both the new identifiers as well as the
+		 * old for compatibility with some BIOSes.
+		 */
+		if (child->device_type != DEVICE_TYPE_INT_LFP &&
+		    child->device_type != DEVICE_TYPE_LFP)
+			continue;
+
+		if (child->i2c_pin)
+		    *i2c_pin = child->i2c_pin;
+
+		/* However, we cannot trust the BIOS writers to populate
+		 * the VBT correctly.  Since LVDS requires additional
+		 * information from AIM blocks, a non-zero addin offset is
+		 * a good indicator that the LVDS is actually present.
+		 */
+		if (child->addin_offset)
+			return true;
+
+		/* But even then some BIOS writers perform some black magic
+		 * and instantiate the device without reference to any
+		 * additional data.  Trust that if the VBT was written into
+		 * the OpRegion then they have validated the LVDS's existence.
+		 */
+		if (dev_priv->opregion.vbt)
+			return true;
+	}
+
+	return false;
+}
+
 /**
  * cdv_intel_lvds_init - setup LVDS connectors on this device
  * @dev: drm device
@@ -576,6 +626,13 @@ void cdv_intel_lvds_init(struct drm_device *dev,
 	struct drm_psb_private *dev_priv = dev->dev_private;
 	u32 lvds;
 	int pipe;
+	u8 pin;
+
+	pin = GMBUS_PORT_PANEL;
+	if (!lvds_is_present_in_vbt(dev, &pin)) {
+		DRM_DEBUG_KMS("LVDS is not present in VBT\n");
+		return;
+	}
 
 	psb_intel_encoder = kzalloc(sizeof(struct psb_intel_encoder),
 				    GFP_KERNEL);