[Intel-gfx] [RFC] Three pipe support for IVB

[Jesse Barnes]

On Thu, 6 Oct 2011 07:31:44 +0100
Dave Airlie <airlied at gmail.com> wrote:

> On Wed, Oct 5, 2011 at 9:18 PM, Keith Packard <keithp at keithp.com> wrote:
> > On Wed, 5 Oct 2011 12:56:47 -0700, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> >
> >> Unfortunately, (2) complicates our mode list output.  If you query for
> >> available modes, you'll definitely see some that you can't drive with 3
> >> pipes enabled.  I'm not sure if the best way to handle that...
> >
> > All we can do is say 'no' when someone tries to select that
> > configuration. We've never figured out a better way to list valid
> > settings.
> >
> > The proposed RandR 1.4 protocol has a 'set everything all at once' API
> > which allows you to say 'no' before even starting the mode setting
> > process, which is kinda nice. We just need to make sure sure this can be
> > mirrored through KMS to the hardware.
> 
> Fine for dynamic stuff, how do you pick a correct initial mode?
> 
> You can't say no there, you need to make a decision from the
> information provided.

Yeah that's a good point.  There's something weird going on in general
with X's default config on my system at least.  All 3 heads come up at
1280x1024, but the two identical HDMI heads come up with different
refresh rates for some reason (one uses the preferred mode and the
other tries to get 75Hz).

Of course I'd prefer an extended config as the default, which might
make it easier to choose all the preferred modes, but that doesn't
solve the problem of having say two 1920x1200 monitors attached along
with a 2560x1600, which won't work on IVB...

Should we add a new mode flag to indicate which modes are conditional
on config and which modes can always be supported?  That way X and
other tools could get all the heads lit up by default at least...

-- 
Jesse Barnes, Intel Open Source Technology Center
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