Re: support for dp 1.2

[Stephen Adler <adler-wRvlPVLobi1/31tCrMuHxg@public.gmane.org>]

On Tue, 2015-06-16 at 16:00 -0400, Ilia Mirkin wrote:
> On Tue, Jun 16, 2015 at 3:53 PM, Stephen Adler <
> adler@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@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.

thanks for all the feed back!

Steve.

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