Re: [PATCH 2/4] drm/i915: Remove WaFbcDisableDpfcClockGating on HSW

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

On Mon, Oct 28, 2013 at 10:22:31AM -0200, Paulo Zanoni wrote:
> 2013/10/27 Daniel Vetter <daniel@ffwll.ch>:
> > On Fri, Oct 25, 2013 at 03:27:50PM -0200, Paulo Zanoni wrote:
> >> 2013/10/24 Ben Widawsky <benjamin.widawsky@intel.com>:
> >> > Production HSW does not need it. I confirmed this with Art.
> >> >
> >> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> >>
> >> I just hope these things don't start uncovering bugs :)
> >>
> >> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> >
> > Merged the first 2 patches of this series. Not sure what to do with the
> > other two, since fbc is essentially disabled on pre-hsw. And no one seems
> > to really work on it :( So I only see minimal reasons to frob with it ...
> 
> IMHO what you said is another reason to actually merge the other two
> patches, since they make FBC-only WAs be applied only on FBC (e.g.,
> probably never).

Another reason would be keeping the codepaths at least somewhat similar.
Could make it a bit easier to fix things later. If it would be me who
gets to fix the FBC mess at some point, I'd try to fix it for all gens
for sure.

At some point I posted a patch to attempt a quick FBC fix for SNB:
"[PATCH] drm/i915: Attempt to fix FBC render tracking with hardware contexts"

In theory that could make FBC work equally well for SNB as it works for
IVB+. And I must confess that I have FBC enabled on my IVB ultrabook
currently since it appears to save a rather significant amount of power.

-- 
Ville Syrjälä
Intel OTC