drm/i915: crt fetch EDID by DVI-I converter on G4x platform

Usually crt mainly get modes via GPIOA ports.
However on G4X platform we need to probe possible
ports for DVI-I, which could be wired to GPIOD,
then fetch our desired EDID, i.e on DG45ID platform
we successfully fetch EDID by GPIOD port.

It fixed freedesktop.org bug #21084

Signed-off-by: Ma Ling <ling.ma@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 27 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 6de97fc66029..af26028c2514 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -428,8 +428,34 @@ static void intel_crt_destroy(struct drm_connector *connector)
 
 static int intel_crt_get_modes(struct drm_connector *connector)
 {
+        int ret;
         struct intel_output *intel_output = to_intel_output(connector);
-        return intel_ddc_get_modes(intel_output);
+        struct intel_i2c_chan *ddcbus;
+        struct drm_device *dev = connector->dev;
+
+
+        ret = intel_ddc_get_modes(intel_output);
+        if (ret || !IS_G4X(dev))
+                goto end;
+
+        ddcbus = intel_output->ddc_bus;
+        /* Try to probe digital port for output in DVI-I -> VGA mode. */
+        intel_output->ddc_bus =
+                intel_i2c_create(connector->dev, GPIOD, "CRTDDC_D");
+
+        if (!intel_output->ddc_bus) {
+                intel_output->ddc_bus = ddcbus;
+                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(intel_output);
+        intel_i2c_destroy(ddcbus);
+
+end:
+        return ret;
+
 }
 
 static int intel_crt_set_property(struct drm_connector *connector,