Re: [PATCH 01/10] drm/i915: No LLC_MLC for HSW.

[Ben Widawsky <ben@bwidawsk.net>]

On Thu, 25 Oct 2012 13:47:22 -0700
Jesse Barnes <jbarnes@virtuousgeek.org> wrote:

> On Mon, 22 Oct 2012 18:34:06 -0700
> Ben Widawsky <ben@bwidawsk.net> wrote:
> 
> > The mid-level cache or as it's more commonly referred to now as L3,
> > is not setup this way on HSW.
> > 
> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> >  drivers/gpu/drm/i915/i915_gem_gtt.c | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > b/drivers/gpu/drm/i915/i915_gem_gtt.c index 47e427e..5751ad2 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > @@ -218,7 +218,11 @@ void i915_ppgtt_bind_object(struct
> > i915_hw_ppgtt *ppgtt, 
> >  	switch (cache_level) {
> >  	case I915_CACHE_LLC_MLC:
> > -		pte_flags |= GEN6_PTE_CACHE_LLC_MLC;
> > +		/* Haswell doesn't set L3 this way */
> > +		if (IS_HASWELL(obj->base.dev))
> > +			pte_flags |= GEN6_PTE_CACHE_LLC;
> > +		else
> > +			pte_flags |= GEN6_PTE_CACHE_LLC_MLC;
> >  		break;
> >  	case I915_CACHE_LLC:
> >  		pte_flags |= GEN6_PTE_CACHE_LLC;
> > @@ -253,12 +257,12 @@ static unsigned int
> > cache_level_to_agp_type(struct drm_device *dev, {
> >  	switch (cache_level) {
> >  	case I915_CACHE_LLC_MLC:
> > -		if (INTEL_INFO(dev)->gen >= 6)
> > -			return AGP_USER_CACHED_MEMORY_LLC_MLC;
> >  		/* Older chipsets do not have this extra level of
> > CPU
> >  		 * cacheing, so fallthrough and request the PTE
> > simply
> >  		 * as cached.
> >  		 */
> > +		if (INTEL_INFO(dev)->gen >= 6 && !IS_HASWELL(dev))
> > +			return AGP_USER_CACHED_MEMORY_LLC_MLC;
> >  	case I915_CACHE_LLC:
> >  		return AGP_USER_CACHED_MEMORY;
> >  	default:
> 
> We might want a .has_mlc or something here at some point, but that
> doesn't have to happen here.
> 
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> 

To be clear, HSW has MLC, (and I'd vote we converge on calling calling
it GPU L3 or something since docs don't seem to use the term MLC
anymore) it just doesn't get set in the PTE anymore.