[Intel-gfx] scaling on ivy bridge

[Daniel Vetter]

On Tue, Oct 09, 2012 at 10:40:26AM -0700, ron minnich wrote:
> I have a display that is, e.g., 2560x1600 on an ivybridge. I'd like to
> set it up so that the software sees a display with half that
> resolution, i.e. the software that draws into the frame buffer (this
> is a bios) can draw into what it sees as a 1280x800 display.
> 
> I've tried a few things but I'm realizing I don't understand the
> ivybridge panel fitter at all. This display is on PIPEA. It appears on
> sandybridge one can write
> PFA_VSCALE, PFA_HSCALE, PFA_WIN_SZ, and PFA_WIN_POS and _PFA_CTL_1 and
> it all works.
> 
> On Ivybridge it seems far more complex. Or am I missing something? I
> don't see any fitting code in the drm driver itself, so I'm not quite
> sure how it's done.
> 
> Thanks in advance, as always.

The panel fitter should work the same on ivb as on snb I think. We only
expose it for integrated panels though, and if the mode you want is
missing you first need to add it. But it should all work ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch