[Nouveau] support for dp 1.2

[Ilia Mirkin]

On Tue, Jun 16, 2015 at 4:15 PM, Stephen Adler <adler at stephenadler.com> wrote:
> On Tue, 2015-06-16 at 16:00 -0400, Ilia Mirkin wrote:
>> On Tue, Jun 16, 2015 at 3:53 PM, Stephen Adler <
>> adler at stephenadler.com> wrote:
>> > On Tue, 2015-06-16 at 15:47 -0400, Ilia Mirkin wrote:
>> > > On Tue, Jun 16, 2015 at 3:33 PM, Stephen Adler <
>> > > adler at stephenadler.com> wrote:
>> > > > Guys,
>> > > >
>> > > > Is there support for display port 1.2 with the nouveau driver
>> > > > and
>> > > > GTX
>> > > > 970?
>> > > >
>> > > > I have a dell 4K monitor and to run it in 4K mode at 60Hz I
>> > > > need to
>> > > > configure the monitor to run version 1.2 of the display port
>> > > > protocol.
>> > > > the nouveau driver works well with display port 1.1 but I only
>> > > > get
>> > > > a
>> > > > 30Hz refresh rate at 4K resolution.
>> > >
>> > > The DP 1.2 540MHz rate should be supported. However there is
>> > > presently
>> > > no MST support, so if the monitor has 2 internal panels, that
>> > > won't
>> > > pan out so well (yet).
>> > >
>> > > Also note that the GTX 970 requires signed firmware from NVIDIA
>> > > to
>> > > use
>> > > any acceleration, and we haven't quite yet figured out how to get
>> > > that
>> > > going. This means that all you get is modesetting, no
>> > > acceleration.
>> > > Esp with a 4K screen, using llvmpipe may feel slow if you use a
>> > > GL
>> > > compositor, as many modern desktops do.
>> > >
>> > >   -ilia
>> > >
>> >
>> > Thanks for the quick response. I'm having a hell of a time with the
>> > nvidia driver since I have three 4K monitors which hook up to the
>> > GTX
>> > 970 card, but in linux it will only drive two of the 3 monitors.
>> > The
>> > monitors do have the dual internal panels each running at 1920x2160
>> > or
>> > something like that. For some reason nvidia only drives 4 of the
>> > panels
>> > (two monitors) per GPU...
>>
>> Kepler+ GPUs only have 4 CRTC's, so you can only scan out 4 things at
>> a time [pre-Kepler have only 2 CRTC's]. However perhaps you can have
>> a
>> single CRTC split an image up into 2 encoders, I don't really know
>> how
>> that works, esp in the context of DP-MST, where it's really a single
>> encoder.
>>
>> >
>> > Is the MST support imminent? or off into the future?
>>
>> It's on the horizon... a horizon, of course, being an imaginary line
>> that keeps moving further away as you attempt to approach it :)
>> Here's
>> Ben's tree from a year ago (which BTW has no support for your GPU at
>> all):
>>
>> http://cgit.freedesktop.org/~darktama/nouveau/log/?h=devel-mst
>>
>> AFAIK he's been putting it off, trying to combine it with a
>> conversion
>> to atomic modesetting.
>>
>>   -ilia
>>
>
> Thanks Ilia, you certianly seem to know what your talking about...
> So... how about this question? Would you be familiar with the Base
> Mosaic and/or SLI mosaic configurations for the nvidia driver?
> specifically if they work with geforce cards? I know they work with
> quadro cards. (At least the base mosaic does with the quadro cards.)
>
> I may just get me another card to solve the 3 monitor problem.

Nope, sorry. Not really familiar with what the blob drivers offer in
that regard. I will say that if the actual HW supports your
configuration (e.g. it works fine in Windows with the exact same
cables / connectors / etc), chances are you can file a bug with them
somehow, not sure what the response rate is though.

I do know that things will go much smoother if all your monitors are
hooked up to a single GPU than to multiple GPU's.

  -ilia