[Intel-gfx] [PATCH v7 3/4] drm/i915/icl: Define MOCS table for Icelake

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-01-07 10:19:44)
> 
> On 05/01/2019 01:33, Lucas De Marchi wrote:
> > On Fri, Dec 21, 2018 at 12:29:41PM +0000, Tvrtko Ursulin wrote:
> >>
> >> On 14/12/2018 18:20, Lucas De Marchi wrote:
> >> we were setting unused entries to uncached, on Icelake they will be set to
> >> whatever all zeros is - LE_PAGETABLE?
> >>
> >> If that is not desired, we may need to transition to a scheme where struct
> >> drm_i915_mocs_entry starts holding the table index, and the static array is
> >> not indexed by it.
> > 
> > agreed
> > 
> >>
> >> It would also save the unused hole of zeros on Icelake which would probably
> >> offset the extra used space.
> > 
> > well, but at the expense of the additional field on the used entries and
> > additional complexity in the code - we would lose the logic here to
> > override an entry unless we keep track what has already been set.
> 
> Yes agreed. If everyone is OK to have unused entries be different 
> semantics per platforms (Icelake = LE_PAGETABLE, others = LE_UC) then as 
> said before, lets just add the commentary to the commit message and fix 
> up all the comments.

Or precede with the patch to make everyone use PTE for unknown (I've
argued that is better wrt to kernel domain tracking ;)
-Chris