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, 12 insertions, 21 deletions

diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c
index d8a586b41275..1ee0dbbf6ee1 100644
--- a/drivers/gpu/drm/i915/intel_dvo.c
+++ b/drivers/gpu/drm/i915/intel_dvo.c
@@ -72,7 +72,7 @@ static const struct intel_dvo_device intel_dvo_devices[] = {
 		.name = "ch7017",
 		.dvo_reg = DVOC,
 		.slave_addr = 0x75,
-		.gpio = GPIOE,
+		.gpio = GMBUS_PORT_DPD,
 		.dev_ops = &ch7017_ops,
 	}
 };
@@ -81,6 +81,7 @@ struct intel_dvo {
 	struct intel_encoder base;
 
 	struct intel_dvo_device dev;
+	int ddc_bus;
 
 	struct drm_display_mode *panel_fixed_mode;
 	bool panel_wants_dither;
@@ -235,13 +236,15 @@ static enum drm_connector_status intel_dvo_detect(struct drm_connector *connecto
 static int intel_dvo_get_modes(struct drm_connector *connector)
 {
 	struct intel_dvo *intel_dvo = intel_attached_dvo(connector);
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
 
 	/* We should probably have an i2c driver get_modes function for those
 	 * devices which will have a fixed set of modes determined by the chip
 	 * (TV-out, for example), but for now with just TMDS and LVDS,
 	 * that's not the case.
 	 */
-	intel_ddc_get_modes(connector, intel_dvo->base.ddc_bus);
+	intel_ddc_get_modes(connector,
+			    &dev_priv->gmbus[intel_dvo->ddc_bus].adapter);
 	if (!list_empty(&connector->probed_modes))
 		return 1;
 
@@ -341,10 +344,10 @@ intel_dvo_get_current_mode(struct drm_connector *connector)
 
 void intel_dvo_init(struct drm_device *dev)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_encoder *intel_encoder;
 	struct intel_dvo *intel_dvo;
 	struct intel_connector *intel_connector;
-	struct i2c_adapter *i2cbus = NULL;
 	int ret = 0;
 	int i;
 	int encoder_type = DRM_MODE_ENCODER_NONE;
@@ -364,15 +367,13 @@ void intel_dvo_init(struct drm_device *dev)
 			 &intel_dvo_enc_funcs, encoder_type);
 
 	/* Set up the DDC bus */
-	intel_encoder->ddc_bus = intel_i2c_create(intel_encoder,
-						  GPIOD, "DVODDC_D");
-	if (!intel_encoder->ddc_bus)
-		goto free_intel;
+	intel_dvo->ddc_bus = GMBUS_PORT_DPB;
 
 	/* Now, try to find a controller */
 	for (i = 0; i < ARRAY_SIZE(intel_dvo_devices); i++) {
 		struct drm_connector *connector = &intel_connector->base;
 		const struct intel_dvo_device *dvo = &intel_dvo_devices[i];
+		struct i2c_adapter *i2c;
 		int gpio;
 
 		/* Allow the I2C driver info to specify the GPIO to be used in
@@ -382,23 +383,18 @@ void intel_dvo_init(struct drm_device *dev)
 		if (dvo->gpio != 0)
 			gpio = dvo->gpio;
 		else if (dvo->type == INTEL_DVO_CHIP_LVDS)
-			gpio = GPIOB;
+			gpio = GMBUS_PORT_PANEL;
 		else
-			gpio = GPIOE;
+			gpio = GMBUS_PORT_DPD;
 
 		/* Set up the I2C bus necessary for the chip we're probing.
 		 * It appears that everything is on GPIOE except for panels
 		 * on i830 laptops, which are on GPIOB (DVOA).
 		 */
-		if (i2cbus != NULL)
-			intel_i2c_destroy(i2cbus);
-		i2cbus = intel_i2c_create(intel_encoder, gpio,
-					  gpio == GPIOB ?  "DVOI2C_B" : "DVOI2C_E");
-		if (i2cbus == NULL)
-			continue;
+		i2c = &dev_priv->gmbus[gpio].adapter;
 
 		intel_dvo->dev = *dvo;
-		ret = dvo->dev_ops->init(&intel_dvo->dev, i2cbus);
+		ret = dvo->dev_ops->init(&intel_dvo->dev, i2c);
 		if (!ret)
 			continue;
 
@@ -451,11 +447,6 @@ void intel_dvo_init(struct drm_device *dev)
 		return;
 	}
 
-	intel_i2c_destroy(intel_encoder->ddc_bus);
-	/* Didn't find a chip, so tear down. */
-	if (i2cbus != NULL)
-		intel_i2c_destroy(i2cbus);
-free_intel:
 	drm_encoder_cleanup(&intel_encoder->base);
 	kfree(intel_dvo);
 	kfree(intel_connector);