[Intel-gfx] [PATCH 4/7] drm/i915: properly set ppgtt cacheability on snb

[Daniel Vetter]

On Tue, Apr 10, 2012 at 03:11:07PM -0700, Ben Widawsky wrote:
> On Sat, Mar 31, 2012 at 11:22:00AM +0200, Daniel Vetter wrote:
> > For some reason snb has 2 fields to set ppgtt cacheability. This one
> > here does not exist on gen7.
> > 
> > This might explain why ppgtt wasn't a win on snb like on ivb - not
> > enough pte caching.
> 
> So, is it a win now?

I've later noticed that the register is part of the bsd block, so I've
figured I'm not gonna benchmark vaapi. I'm a lazy bastard.

> > Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > ---
> >  drivers/gpu/drm/i915/i915_gem.c |    3 +++
> >  drivers/gpu/drm/i915/i915_reg.h |    4 ++++
> >  2 files changed, 7 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index 5dc5f42..cab70ef 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -3766,6 +3766,9 @@ void i915_gem_init_ppgtt(struct drm_device *dev)
> >  	if (INTEL_INFO(dev)->gen == 6) {
> >  		uint32_t ecochk, gab_ctl, ecobits;
> >  
> > +		ecobits = I915_READ(GAC_ECO_BITS); 
> > +		I915_WRITE(GAC_ECO_BITS, ecobits | ECOBITS_PPGTT_CACHE64B);
> > +
> >  		gab_ctl = I915_READ(GAB_CTL);
> >  		I915_WRITE(GAB_CTL, gab_ctl | GAB_CTL_CONT_AFTER_PAGEFAULT);
> >  
> 
> Is this a bad rebase? This doesn't apply to whatever I am using.

Mucks around in the same area as the previous patch and hence conflicts
without that applied.

> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index e72c251..5457980 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -125,6 +125,10 @@
> >  #define   ECOCHK_PPGTT_CACHE64B		(0x3<<3)
> >  #define   ECOCHK_PPGTT_CACHE4B		(0x0<<3)
> >  
> > +#define GAC_ECO_BITS			0x14090
> > +#define   ECOBITS_PPGTT_CACHE64B	(3<<8)
> > +#define   ECOBITS_PPGTT_CACHE4B		(0<<8)
> > +
> >  #define GAB_CTL				0x24000
> >  #define   GAB_CTL_CONT_AFTER_PAGEFAULT	(1<<8)
> >  
> 
> According to bspec, but 13 must be set to a 1 also.

I've checked and bit13 seems to be set already on my snb, so I've just
or'ed in the missing bits.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48