drm/i915: Improve CRTDDC mapping by using VBT info

Use VBT information to determine which DDC bus to use for CRTDCC.
Fall back to GPIOA if VBT info is not available.

Signed-off-by: David Müller <d.mueller@elsoft.ch>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Tested on: 855 (David), and 945GM, 965GM, GM45, and G45 (anholt)

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index d1294978a38c..590f81c8f594 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -508,6 +508,7 @@ void intel_crt_init(struct drm_device *dev)
 {
         struct drm_connector *connector;
         struct intel_output *intel_output;
+        struct drm_i915_private *dev_priv = dev->dev_private;
         u32 i2c_reg;
 
         intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL);
@@ -527,8 +528,12 @@ void intel_crt_init(struct drm_device *dev)
         /* Set up the DDC bus. */
         if (IS_IGDNG(dev))
                 i2c_reg = PCH_GPIOA;
-        else
+        else {
                 i2c_reg = GPIOA;
+                /* Use VBT information for CRT DDC if available */
+                if (dev_priv->crt_ddc_bus != -1)
+                        i2c_reg = dev_priv->crt_ddc_bus;
+        }
         intel_output->ddc_bus = intel_i2c_create(dev, i2c_reg, "CRTDDC_A");
         if (!intel_output->ddc_bus) {
                 dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "