drm/i915: move VBT based LVDS presence check to intel_bios.c

Hide knowledge about VBT child devices in intel_bios.c.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458125015-7931-2-git-send-email-jani.nikula@intel.com

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index d5e6da01adaa..4f7eba36a849 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -1472,3 +1472,53 @@ bool intel_bios_is_tv_present(struct drm_i915_private *dev_priv)
 
 	return false;
 }
+
+/**
+ * intel_bios_is_lvds_present - is LVDS present in VBT
+ * @dev_priv:	i915 device instance
+ * @i2c_pin:	i2c pin for LVDS if present
+ *
+ * Return true if LVDS is present. If no child devices were parsed from VBT,
+ * assume LVDS is present.
+ */
+bool intel_bios_is_lvds_present(struct drm_i915_private *dev_priv, u8 *i2c_pin)
+{
+	int i;
+
+	if (!dev_priv->vbt.child_dev_num)
+		return true;
+
+	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
+		union child_device_config *uchild = dev_priv->vbt.child_dev + i;
+		struct old_child_dev_config *child = &uchild->old;
+
+		/* 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 (intel_gmbus_is_valid_pin(dev_priv, 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;
+}