[PATCH] drm/radeon/kms: fix tv dac conflict resolver

[Dave Airlie]

On Sat, May 1, 2010 at 10:42 PM, GhePeU <ghepeu at virgilio.it> wrote:
> Il giorno mar, 27/04/2010 alle 18.57 -0400, Alex Deucher ha scritto:
>> On Tue, Apr 27, 2010 at 6:24 PM, GhePeU <ghepeu at virgilio.it> wrote:
>> > Il giorno mar, 27/04/2010 alle 18.11 -0400, Alex Deucher ha scritto:
>> >> On Tue, Apr 27, 2010 at 5:30 PM, GhePeU <ghepeu at virgilio.it> wrote:
>> >> > Il giorno gio, 15/04/2010 alle 13.41 -0400, Alex Deucher ha scritto:
>> >> >> >From 837feb147c531219c7315857a6f17e145af8f750 Mon Sep 17 00:00:00 2001
>> >> >> From: Alex Deucher <alexdeucher at gmail.com>
>> >> >> Date: Thu, 15 Apr 2010 13:31:12 -0400
>> >> >> Subject: [PATCH] drm/radeon/kms: fix tv dac conflict resolver
>> >> >
>> >> > Hi,
>> >> >
>> >> > a few days ago I upgraded to the last 2.6.34 rc kernel and found that with
>> >> > KMS both the console and X were using a 800x600 resolution instead of my LCD
>> >> > display's native resolution of 1440x900 who was selected by default with
>> >> > 2.6.33 and previous kernels.
>> >> >
>> >> > I tracked the problem to this patch, which causes the same issues also
>> >> > when manually applied to 2.6.33: apparently the kms radeon driver
>> >> > wrongly detects a TV connected to my card (I don't have one, only a LCD
>> >> > display connected to the DVI port) and forces the TV default resolution
>> >> > for all the outputs.
>> >>
>> >> You issue is not related to the patch.  What the patch does is allow
>> >> you to use the digital part of DVI plus TV at the same time.  The
>> >> analog part of the DVI port and the TV share the same DAC so they
>> >> can't be used at the same time.  Prior to the patch, both the TV and
>> >> DVI were detected as attached, but the TV was always disabled since it
>> >> was wrongly seen as conflicting with the DVI.
>> >>
>> >> Your issue is actually a matter of load detection for TV not always
>> >> being reliable.  I don't know what a proper fix would be.  We could
>> >> disable load detection for TV to avoid false positives, but that would
>> >> prevent automatic detection of TV which does work in most cases.
>> >>
>> >> Alex
>> >>
>> >
>> > With UMS however I don't have this problem, is the logic different?
>> >
>> > Shouldn't the driver behavior with KMS be the same, in this case? At
>> > least there wouldn't be (apparent) regressions like the one I'm
>> > experiencing.
>> >
>>
>> UMS does not enable load detection on TV by default while KMS does,
>> the difference being KMS provides both the console and X so you want
>> to make sure you put something up on whatever monitors or tvs happen
>> to be attached.  I'm not sure what the best answer is here.
>>
>> Alex
>
> Would it be possible to add a module option to disable tv load
> detection? As things are now I must always change back the resolution to
> 1440x900 and disable the TV.

try booting with video=TV-1:d

Dave.