[Intel-gfx] [RFCv2 2/3] drm/i915: Introduce private PAT management

[Chris Wilson]

Quoting Chris Wilson (2017-08-22 19:01:11)
> Quoting Zhi Wang (2017-08-23 02:44:12)
> > The private PAT management is to support both static and dynamic PPAT
> > entry manipulation. During the initialization, the PPAT indexes with
> > specific PPAT values could be reserved and set by intel_ppat_reserve.
> > The unused PPAT entries can be allocated/freed later at runtime. Two
> > APIs are introduced for dynamically managing PPAT entries: intel_ppat_get
> > and intel_ppat_set.
> 
> What's the use case for reserved? Once assigned, a new allocation
> doesn't evict, so reservation is just another form of assignment.

Or rather, I can see the differentiation you want for init, but I can't
see why you want to export it (since it ignores the ppat controller) or
why you need to have a reserved bit, since you can just elevate the
refcount.
-Chris