[Intel-gfx] [PATCH] drm/i915: Fix DDC bus selection for multifunction SDVO
ajax at redhat.com
Thu May 6 09:01:51 PDT 2010
On Wed, 2010-05-05 at 15:38 +0800, ykzhao wrote:
> Hi, Ajax
> Using the BIOS-defined value in VBT can fix the bug you mentioned.
> but the problem is that it is static and would still have problem if
> user does outputs swap on a multiple function SDVO device at run
> time(E.g. The external monitor is changed from SDVO-VGA to SDVO-DVI).
> Indeed, there is a SDVO specification that we use to write the SDVO
> code(Unfortunately, it's not white-washed yet to be released publicly).
> There is a predefined priority scheme described in the specification
> that driver and HW vendor need to follow, in order to pick up the
> correct DDC bus on the SDVO device that supports multiple outputs. For
> example, the RGB0 will have higher priority than TMDS0 if both
> RGB0/TMDS0 exist. RGB0 should use DDC1 and TMDS0 use the DDC2.)
> What do you think the following patch? Would it work for the bug
> reported on redhat bugzilla584229?
I don't think this is correct, though I haven't tried it. RGB0 and
TMDS0 are both going to be the same DVI connector for DVI-I. If they
use different DDC buses, one of them won't get DDC, ever, since DVI-I
only has one set of DDC pins.
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