[Intel-gfx] [PATCH] drm/i915: Fix DDC bus selection for multifunction SDVO

[Adam Jackson]

On Fri, 2010-04-23 at 16:16 -0400, Adam Jackson wrote:
> 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.

Just to follow up on this, we're shipping the following two patches in
F13 gold kernel:

http://cvs.fedoraproject.org/viewvc/rpms/kernel/F-13/drm-intel-sdvo-fix.patch?revision=1.1&content-type=text%2Fplain&view=co
http://cvs.fedoraproject.org/viewvc/rpms/kernel/F-13/drm-intel-sdvo-fix-2.patch?revision=1.1&content-type=text%2Fplain&view=co

And, combined, they appear to fix DVI-I on at least one machine:

http://bugzilla.redhat.com/584229

I'm still skeptical of any approach that involves having to guess which
DDC bus belongs to which connector.  The only thing that seems remotely
sane to me is trusting the wiring table in the SDVO card itself.

- ajax
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