[Intel-gfx] [PATCH 08/16] drm/i915: avoid the last 8mb of stolen on BDW/SKL

[Zanoni, Paulo R]

Em Sáb, 2015-08-15 às 09:29 +0100, Chris Wilson escreveu:
> On Fri, Aug 14, 2015 at 06:34:13PM -0300, Paulo Zanoni wrote:
> > The FBC hardware for these platforms doesn't have access to the
> > bios_reserved range, so it always assumes the maximum (8mb) is 
> > used.
> > So avoid this range while allocating.
> > 
> > This solves a bunch of FIFO underruns that happen if you end up
> > putting the CFB in that memory range. On my machine, with 32mb of
> > stolen, I need a 2560x1440 mode for that.
> 
> If the restriction applies only to FBC, apply it to only fbc.

That's what the patch is doing. The part where we set the unusual
start/end is at intel_fbc.c:find_compression_threshold(). Everything
else should be behaving just as before.

Maybe you're being confused by the addition of the stolen_usable_size
variable.

> -Chris
>