drm/i915: Fix DDC bus selection for multifunction SDVO

Multifunction SDVO cards stopped working after 14571b4, and would report
something that looked remarkably like an ADD2 SPD ROM instead of EDID.
This appears to be because DDC bus selection was utterly horked by that
commit; controlled_output was no longer always a single bit, so
intel_sdvo_select_ddc_bus would pick bus 0, which is (unsurprisingly)
the SPD ROM bus, not a DDC bus.

So, instead of that, let's just use the DDC bus the child device table
tells us to use.  I'm guessing at the bitmask and shifting from VBIOS
dumps, but it can't possibly be worse.

cf. https://bugzilla.redhat.com/584229

Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index f9ba452f0cbf..4c748d8f73d6 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -366,6 +366,7 @@ parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
                         p_mapping->dvo_port = p_child->dvo_port;
                         p_mapping->slave_addr = p_child->slave_addr;
                         p_mapping->dvo_wiring = p_child->dvo_wiring;
+                        p_mapping->ddc_pin = p_child->ddc_pin;
                         p_mapping->initialized = 1;
                 } else {
                         DRM_DEBUG_KMS("Maybe one SDVO port is shared by "