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, 8 insertions, 40 deletions

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 2353da625d25..8b782ee63085 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -264,12 +264,13 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 static bool intel_crt_detect_ddc(struct drm_encoder *encoder)
 {
 	struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
+	struct drm_i915_private *dev_priv = encoder->dev->dev_private;
 
 	/* CRT should always be at 0, but check anyway */
 	if (intel_encoder->type != INTEL_OUTPUT_ANALOG)
 		return false;
 
-	return intel_ddc_probe(intel_encoder);
+	return intel_ddc_probe(intel_encoder, dev_priv->crt_ddc_pin);
 }
 
 static enum drm_connector_status
@@ -445,29 +446,18 @@ static void intel_crt_destroy(struct drm_connector *connector)
 
 static int intel_crt_get_modes(struct drm_connector *connector)
 {
-	struct intel_encoder *encoder = intel_attached_encoder(connector);
-	struct i2c_adapter *ddc_bus;
 	struct drm_device *dev = connector->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
-	ret = intel_ddc_get_modes(connector, encoder->ddc_bus);
+	ret = intel_ddc_get_modes(connector,
+				 &dev_priv->gmbus[dev_priv->crt_ddc_pin].adapter);
 	if (ret || !IS_G4X(dev))
-		goto end;
+		return ret;
 
 	/* Try to probe digital port for output in DVI-I -> VGA mode. */
-	ddc_bus = intel_i2c_create(encoder, GPIOD, "CRTDDC_D");
-	if (!ddc_bus) {
-		dev_printk(KERN_ERR, &connector->dev->pdev->dev,
-			   "DDC bus registration failed for CRTDDC_D.\n");
-		goto end;
-	}
-	/* Try to get modes by GPIOD port */
-	ret = intel_ddc_get_modes(connector, ddc_bus);
-	intel_i2c_destroy(ddc_bus);
-
-end:
-	return ret;
-
+	return intel_ddc_get_modes(connector,
+				   &dev_priv->gmbus[GMBUS_PORT_DPB].adapter);
 }
 
 static int intel_crt_set_property(struct drm_connector *connector,
@@ -513,7 +503,6 @@ void intel_crt_init(struct drm_device *dev)
 	struct intel_encoder *intel_encoder;
 	struct intel_connector *intel_connector;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 i2c_reg;
 
 	intel_encoder = kzalloc(sizeof(struct intel_encoder), GFP_KERNEL);
 	if (!intel_encoder)
@@ -534,27 +523,6 @@ void intel_crt_init(struct drm_device *dev)
 
 	intel_connector_attach_encoder(intel_connector, intel_encoder);
 
-	/* Set up the DDC bus. */
-	if (HAS_PCH_SPLIT(dev))
-		i2c_reg = PCH_GPIOA;
-	else {
-		i2c_reg = GPIOA;
-		/* Use VBT information for CRT DDC if available */
-		if (dev_priv->crt_ddc_bus != 0)
-			i2c_reg = dev_priv->crt_ddc_bus;
-	}
-	intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-						  i2c_reg, "CRTDDC_A");
-	if (!intel_encoder->ddc_bus) {
-		dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
-			   "failed.\n");
-		drm_connector_cleanup(&intel_connector->base);
-		kfree(intel_connector);
-		drm_encoder_cleanup(&intel_encoder->base);
-		kfree(intel_encoder);
-		return;
-	}
-
 	intel_encoder->type = INTEL_OUTPUT_ANALOG;
 	intel_encoder->clone_mask = (1 << INTEL_SDVO_NON_TV_CLONE_BIT) |
 				   (1 << INTEL_ANALOG_CLONE_BIT) |