Re: [PATCH] drm/i915: Correctly populate user mode h/vdisplay with pipe src size during readout

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, May 02, 2018 at 04:33:30PM +0100, Chris Wilson wrote:
> Quoting Ville Syrjala (2018-04-26 17:30:15)
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > During state readout we first read out the pipe src size, store
> > that information in the user mode h/vdisplay, but later on we overwrite
> > that with the actual crtc timings. That makes our read out crtc state
> > inconsistent with itself when the BIOS has enabled the panel fitter to
> > scale the pipe contents. Let's preserve the pipe src size based
> > information in the user mode to make things consistent again.
> 
> The question I don't feel answered is: If this is the BIOS mode, why
> aren't we filling it from get_hw_state?

I suppose the answer is that we're only filling out the bare minimum
of information during the basic readout. That is everything we need
for intel_pipe_config_compare() to do its job. Later on we fill the
gaps to make the state actually presentable to userspace. We don't
have to do that if the state we read out isn't actually going to be
exposed to userspace.

I suppose we could consider doing a more thorough job up front, but
I think we'd need to spend some though on eg. the handling of the
mode blob. We probably wouldn't want userspace to gain access to
our short lived internal mode blob created from the read out state.

-- 
Ville Syrjälä
Intel
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx