drm/i915: use GMBUS to manage i2c links

Use the GMBUS interface rather than direct bit banging to grab the EDID
over DDC (and for other forms of auxiliary communication with external
display controllers). The hope is that this method will be much faster
and more reliable than bit banging for fetching EDIDs from buggy monitors
or through switches, though we still preserve the bit banging as a
fallback in case GMBUS fails.

Based on an original patch by Jesse Barnes.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 3 insertions, 13 deletions

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 2ff4a5cb2d56..9177c17853e5 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -474,11 +474,12 @@ static int intel_lvds_get_modes(struct drm_connector *connector)
 {
 	struct intel_lvds *intel_lvds = intel_attached_lvds(connector);
 	struct drm_device *dev = connector->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_display_mode *mode;
 
 	if (intel_lvds->edid_good) {
 		int ret = intel_ddc_get_modes(connector,
-					      intel_lvds->base.ddc_bus);
+					      &dev_priv->gmbus[GMBUS_PORT_PANEL].adapter);
 		if (ret)
 			return ret;
 	}
@@ -898,21 +899,12 @@ void intel_lvds_init(struct drm_device *dev)
 	 *    if closed, act like it's not there for now
 	 */
 
-	/* Set up the DDC bus. */
-	intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-						  gpio, "LVDSDDC_C");
-	if (!intel_encoder->ddc_bus) {
-		dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
-			   "failed.\n");
-		goto failed;
-	}
-
 	/*
 	 * Attempt to get the fixed panel mode from DDC.  Assume that the
 	 * preferred mode is the right one.
 	 */
 	intel_lvds->edid_good = true;
-	if (!intel_ddc_get_modes(connector, intel_encoder->ddc_bus))
+	if (!intel_ddc_get_modes(connector, &dev_priv->gmbus[GMBUS_PORT_PANEL].adapter))
 		intel_lvds->edid_good = false;
 
 	if (!intel_lvds->edid_good) {
@@ -999,8 +991,6 @@ out:
 
 failed:
 	DRM_DEBUG_KMS("No LVDS modes found, disabling.\n");
-	if (intel_encoder->ddc_bus)
-		intel_i2c_destroy(intel_encoder->ddc_bus);
 	drm_connector_cleanup(connector);
 	drm_encoder_cleanup(encoder);
 	kfree(intel_lvds);