[Intel-gfx] [PATCH 1/7] drm/i915: Allocate a common scratch page

[Chris Wilson]

Quoting Mika Kuoppala (2018-12-04 15:07:01)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Currently we allocate a scratch page for each engine, but since we only
> > ever write into it for post-sync operations, it is not exposed to
> > userspace nor do we care for coherency. As we then do not care about its
> > contents, we can use one page for all, reducing our allocations and
> > avoid complications by not assuming per-engine isolation.
> >
> > For later use, it simplifies engine initialisation (by removing the
> > allocation that required struct_mutex!) and means that we can always rely
> > on there being a scratch page.
> >
> > v2: Check that we allocated a large enough scratch for I830 w/a
> >
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> 
> Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

Plonked it in since it can serve for our need of a backport to fix
v4.18.20. Thanks,
-Chris