Re: [PATCH 09/10] drm/i915: flush system agent TLBs on SNB

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Tue, 23 Oct 2012 16:28:53 +0200
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Tue, Oct 23, 2012 at 07:17:53AM -0700, Jesse Barnes wrote:
> > On Mon, 22 Oct 2012 18:34:14 -0700
> > Ben Widawsky <ben@bwidawsk.net> wrote:
> > 
> > > This allows us to map the PTEs WC. I've not done thorough testing or
> > > performance measurements with this patch, but it should be decent.
> > > 
> > > This is based on a patch from Jesse with the original commit message
> > > > I've only lightly tested this so far, but the corruption seems to be
> > > > gone if I write the GFX_FLSH_CNTL reg after binding an object.  This
> > > > register should control the TLB for the system agent, which is what CPU
> > > > mapped objects will go through.
> > > 
> > > It has been updated for the new AGP-less code by me, and included with
> > > it is feedback from the original patch.
> > > 
> > > CC: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > > ---
> > >  drivers/gpu/drm/i915/i915_gem_gtt.c | 5 +++--
> > >  drivers/gpu/drm/i915/i915_reg.h     | 2 ++
> > >  2 files changed, 5 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > index 16fe960..e5f0a7f 100644
> > > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > > @@ -391,6 +391,7 @@ static void gen6_ggtt_bind_object(struct drm_i915_gem_object *obj,
> > >  	}
> > >  
> > >  out:
> > > +	I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
> > >  	/* XXX: This serves as a posting read preserving the way the old code
> > >  	 * works. It's not clear if this is strictly necessary or just voodoo
> > >  	 * based on what I've tried to gather from the docs.
> > > @@ -593,8 +594,8 @@ int i915_gem_gtt_init(struct drm_device *dev)
> > >  	if (ret)
> > >  		return ret;
> > >  
> > > -	dev_priv->mm.gtt->gtt = ioremap(gtt_bus_addr,
> > > -					dev_priv->mm.gtt->gtt_total_entries * sizeof(gtt_pte_t));
> > > +	dev_priv->mm.gtt->gtt = ioremap_wc(gtt_bus_addr,
> > > +					   dev_priv->mm.gtt->gtt_total_entries * sizeof(gtt_pte_t));
> > >  
> > >  	/* GMADR is the PCI aperture used by SW to access tiled GFX surfaces in a linear fashion. */
> > >  	DRM_DEBUG_DRIVER("GMADR size = %dM\n", dev_priv->mm.gtt->gtt_mappable_entries >> 8);
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > > index 1d54328..e8c578f 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -683,6 +683,8 @@
> > >  #define   CM0_RC_OP_FLUSH_DISABLE (1<<0)
> > >  #define BB_ADDR		0x02140 /* 8 bytes */
> > >  #define GFX_FLSH_CNTL	0x02170 /* 915+ only */
> > > +#define GFX_FLSH_CNTL_GEN6	0x101008
> > > +#define   GFX_FLSH_CNTL_EN	(1<<0)
> > >  #define ECOSKPD		0x021d0
> > >  #define   ECO_GATING_CX_ONLY	(1<<3)
> > >  #define   ECO_FLIP_DONE		(1<<0)
> > 
> > Looks good.  Has anyone tried this on gen3-5?
> 
> pre-gen6 still use the intel_gtt code, since we need to for the next
> decade or so to keep ums (and crappy xvmc on gen3) going.

Flush needs to happen somewhere though...

-- 
Jesse Barnes, Intel Open Source Technology Center