[Intel-gfx] [PATCH] drm/i915: Transform whitelisting WAs into a simple reg write

[Chris Wilson]

Quoting Mika Kuoppala (2017-10-04 13:39:13)
> Oscar Mateo <oscar.mateo at intel.com> writes:
> 
> > RING_FORCE_TO_NONPRIV registers do not live in the logical context. They are simply
> > global privileged MMIO registers that happen to be powercontext saved and restored
> > (meaning only they can survive RC6). Therefore, there is absolutely no need to save
> > them so that they can be restored everytime we create a new logical context.
> >
> > Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_engine_cs.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> > index a28e2a8..a75f5e8 100644
> > --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> > @@ -845,8 +845,8 @@ static int wa_ring_whitelist_reg(struct intel_engine_cs *engine,
> >       if (WARN_ON(index >= RING_MAX_NONPRIV_SLOTS))
> >               return -EINVAL;
> >  
> > -     WA_WRITE(RING_FORCE_TO_NONPRIV(engine->mmio_base, index),
> > -              i915_mmio_reg_offset(reg));
> > +     I915_WRITE(RING_FORCE_TO_NONPRIV(engine->mmio_base, index),
> > +                i915_mmio_reg_offset(reg));
> 
> #define WA_WRITE should also been removed as it is clearly
> dangerous. Chris pointed out that anything with nonmasked access
> is not part of context image, and this seems to hold true in
> atleast with current cases.
> 
> But removing of define can be a followup.

I've picked up this patch and I'll squash in the -WA_WRITE into the
removal of WA_SET_BIT and push all 3 patches at once (when the shards
report back).

Thanks for the patch, review, testing, debate and keep having fun.
-Chris