[Intel-gfx] [PATCH] drm/i915: Check for a change in fb size, and reconfigure the pipe

[Chris Wilson]

On Tue, 13 Nov 2012 15:15:55 +0200, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> On Tue, Nov 13, 2012 at 12:48:11PM +0000, Chris Wilson wrote:
> > On Tue, 13 Nov 2012 14:42:36 +0200, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> > > On Tue, Nov 13, 2012 at 12:15:10PM +0000, Chris Wilson wrote:
> > > > In the slightly unusual case where the pipe is programmed to the same
> > > > modeline, but the framebuffer is a new size, we need to resetup the
> > > > panel fitter as appropriate and this requires a full modeset. This can
> > > > only occur currently as part of the BIOS takeover where there are
> > > > slightly different semantics governing how the panel fitter and
> > > > framebuffer is programmed relative to the modeline.
> > > 
> > > Hmm. I don't get it. Why would the framebuffer size affect the panel
> > > fitter configuration?
> > 
> > The BIOS uses fb->(width,height) to program PIPESRC, we use
> > mode->[hv]display. The BIOS's semantics makes more sense
> 
> I don't think so. That would make panning impossible.

True. The issue really appears that we recreate the mode using the crtc
values and assume that the reverse mapping works. Further issues arise
if we want to recover any offsets in a multiple output configuration. I
will just have to double-check that the BIOS configuration matches our
usage.

And I whole-heartedly agree with separating the display mode from the
plane configuration, I guess you have something planned along those
lines already ;-)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre