[Intel-gfx] [PATCH v2 14/24] drm/i915: Finish gen6/7 dynamic page table allocation

[Daniel Vetter]

On Tue, Jan 13, 2015 at 11:53:22AM +0000, Michel Thierry wrote:
> On 1/5/2015 2:45 PM, Daniel Vetter wrote:
> >Aside: Should we only allocate the scratch_pt for !aliasing?
> The next patch version will have the changes.
> About the scratch_pt, I'm not sure if it's a requirement in gen6/7 (to point
> unused page tables to the scratch, e.g. if there's less than 2GB).
> We know in gen8 that's the case, and systems with less than 4GB must have
> the remaining PDPs set to scratch page.

Assuming I understand things correctly we need the scratch_pt for
replacing the intermediate levels to collapse the tree a bit. Which is
useful both on gen7 and gen8+.

My question was to move the allocation into the full-ppgtt code (i.e.
i915.enable_ppgtt=2, not =1) since we don't really need this for aliasing
ppgtt mode. That should help a bit with readability since it makes it
clearer which things are used in which modes of the driver.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch