[Solved] Re: Dual head on ATI FirePro M5800

[Alex Deucher]

On Mon, Oct 25, 2010 at 9:24 AM, Ole Tange <ole at tange.dk> wrote:
> On Wed, Oct 20, 2010 at 10:51 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
>> On Wed, Oct 20, 2010 at 10:09 AM, Ole Tange <ole at tange.dk> wrote:
>>> On Tue, Oct 5, 2010 at 1:37 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
>>>> On Mon, Oct 4, 2010 at 5:37 PM, Ole Tange <ole at tange.dk> wrote:
>>>>> I am trying to get dual head on ATI FirePro M5800 working. LVDS works,
>>>>> but VGA-0 is in power save mode no matter what I do.
>>>>>
>>>>> My colleague got the non-free driver working, but I would prefer using
>>>>> the free driver. My research seems to indicate the chipset is called
>>>>> Redwood or r8xx or RV830 or r800 or Evergreen - but I could be wrong.
>>>>>
>>>>> I have been unable to find a guide for this card and the obvious
>>>>> (xrandr --output LVDS --output VGA-0 --left-of LVDS) does not work.
>>>>> Neither does KDE's gui config of display.
>
> The problem was that /etc/modules did not contain 'radeon'. After
> adding that and rebooting everything worked.
>
> I also tried 'modprobe radeon' while running X. This is is not
> recommendable: Apparently that confused X so the display got screwed
> up but X kept running.

If you want to use KMS, you need to load the drm before starting X as
both the drm and the ddx are capable of modesetting, but you only want
1 driver doing the modesetting.  When the drm is loaded in kms mode,
the ddx uses the drm for modesetting.  when the drm is not loaded, the
ddx programs the hw directly.

Alex