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, 13 insertions, 25 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 783924c7682a..f814cb035e01 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -40,6 +40,7 @@
 struct intel_hdmi {
 	struct intel_encoder base;
 	u32 sdvox_reg;
+	int ddc_bus;
 	bool has_hdmi_sink;
 };
 
@@ -148,11 +149,13 @@ static enum drm_connector_status
 intel_hdmi_detect(struct drm_connector *connector)
 {
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
-	struct edid *edid = NULL;
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
+	struct edid *edid;
 	enum drm_connector_status status = connector_status_disconnected;
 
 	intel_hdmi->has_hdmi_sink = false;
-	edid = drm_get_edid(connector, intel_hdmi->base.ddc_bus);
+	edid = drm_get_edid(connector,
+			    &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
 
 	if (edid) {
 		if (edid->input & DRM_EDID_INPUT_DIGITAL) {
@@ -169,12 +172,14 @@ intel_hdmi_detect(struct drm_connector *connector)
 static int intel_hdmi_get_modes(struct drm_connector *connector)
 {
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
 
 	/* We should parse the EDID data and find out if it's an HDMI sink so
 	 * we can send audio to it.
 	 */
 
-	return intel_ddc_get_modes(connector, intel_hdmi->base.ddc_bus);
+	return intel_ddc_get_modes(connector,
+				   &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
 }
 
 static void intel_hdmi_destroy(struct drm_connector *connector)
@@ -246,32 +251,25 @@ void intel_hdmi_init(struct drm_device *dev, int sdvox_reg)
 	/* Set up the DDC bus. */
 	if (sdvox_reg == SDVOB) {
 		intel_encoder->clone_mask = (1 << INTEL_HDMIB_CLONE_BIT);
-		intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-							  GPIOE, "HDMIB");
+		intel_hdmi->ddc_bus = GMBUS_PORT_DPB;
 		dev_priv->hotplug_supported_mask |= HDMIB_HOTPLUG_INT_STATUS;
 	} else if (sdvox_reg == SDVOC) {
 		intel_encoder->clone_mask = (1 << INTEL_HDMIC_CLONE_BIT);
-		intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-							  GPIOD, "HDMIC");
+		intel_hdmi->ddc_bus = GMBUS_PORT_DPC;
 		dev_priv->hotplug_supported_mask |= HDMIC_HOTPLUG_INT_STATUS;
 	} else if (sdvox_reg == HDMIB) {
 		intel_encoder->clone_mask = (1 << INTEL_HDMID_CLONE_BIT);
-		intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-							  PCH_GPIOE, "HDMIB");
+		intel_hdmi->ddc_bus = GMBUS_PORT_DPB;
 		dev_priv->hotplug_supported_mask |= HDMIB_HOTPLUG_INT_STATUS;
 	} else if (sdvox_reg == HDMIC) {
 		intel_encoder->clone_mask = (1 << INTEL_HDMIE_CLONE_BIT);
-		intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-							  PCH_GPIOD, "HDMIC");
+		intel_hdmi->ddc_bus = GMBUS_PORT_DPC;
 		dev_priv->hotplug_supported_mask |= HDMIC_HOTPLUG_INT_STATUS;
 	} else if (sdvox_reg == HDMID) {
 		intel_encoder->clone_mask = (1 << INTEL_HDMIF_CLONE_BIT);
-		intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-							  PCH_GPIOF, "HDMID");
+		intel_hdmi->ddc_bus = GMBUS_PORT_DPD;
 		dev_priv->hotplug_supported_mask |= HDMID_HOTPLUG_INT_STATUS;
 	}
-	if (!intel_encoder->ddc_bus)
-		goto err_connector;
 
 	intel_hdmi->sdvox_reg = sdvox_reg;
 
@@ -288,14 +286,4 @@ void intel_hdmi_init(struct drm_device *dev, int sdvox_reg)
 		u32 temp = I915_READ(PEG_BAND_GAP_DATA);
 		I915_WRITE(PEG_BAND_GAP_DATA, (temp & ~0xf) | 0xd);
 	}
-
-	return;
-
-err_connector:
-	drm_encoder_cleanup(&intel_encoder->base);
-	drm_connector_cleanup(connector);
-	kfree(intel_hdmi);
-	kfree(intel_connector);
-
-	return;
 }