[Intel-gfx] [PATCH] drm/i915: Initialize the aliasing ppgtt as part of global gtt

[Thierry, Michel]

> -----Original Message-----
> From: Daniel Vetter [mailto:daniel.vetter at ffwll.ch] On Behalf Of Daniel
> Vetter
> Sent: Wednesday, August 06, 2014 9:31 AM
> To: Thierry, Michel
> Cc: Daniel Vetter; Intel Graphics Development
> Subject: Re: [PATCH] drm/i915: Initialize the aliasing ppgtt as part of
global gtt
> 
> On Wed, Aug 06, 2014 at 08:18:52AM +0000, Thierry, Michel wrote:
> >
> >
> > > -----Original Message-----
> > > From: Daniel Vetter [mailto:daniel.vetter at ffwll.ch]
> > > Sent: Monday, August 04, 2014 3:19 PM
> > > To: Intel Graphics Development
> > > Cc: Daniel Vetter; Thierry, Michel; Ville Syrjälä
> > > Subject: [PATCH] drm/i915: Initialize the aliasing ppgtt as part of
global gtt
> > >
> > > Stuffing this into the context setup code doesn't make a lot of sense.
> > > Also reusing the real ppgtt setup code makes even less sense since the
> > > aliasing ppgtt isn't a real address space. Leaving all that stuff
> > > unitialized will make sure that we catch any abusers promptly.
> > >
> > > This is also a prep work to clean up the context->ppgtt link.
> > >
> > > v2: Fix up the logic fail, I've fumbled it so badly to completely
> > > disable ppgtt on gen6. Spotted by Ville and Michel. Also move around
> > > the pde write into the gen6 init function, since otherwise it won't
> > > work at all.
> > >
> > > Cc: "Thierry, Michel" <michel.thierry at intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > > ---
> > >  drivers/gpu/drm/i915/i915_gem_context.c | 13 +---------
> > >  drivers/gpu/drm/i915/i915_gem_gtt.c     | 42
> +++++++++++++++++++++++-
> > > ---------
> > >  2 files changed, 31 insertions(+), 24 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c
> > > b/drivers/gpu/drm/i915/i915_gem_context.c
> > > index 3b8367aa8404..7a455fcee3a7 100644
> > > --- a/drivers/gpu/drm/i915/i915_gem_context.c
> > > +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> > > @@ -276,17 +276,6 @@ i915_gem_create_context(struct drm_device
> *dev,
> > >  			goto err_unpin;
> > >  		} else
> > >  			ctx->vm = &ppgtt->base;
> > > -
> > > -		/* This case is reserved for the global default context and
> > > -		 * should only happen once. */
> > > -		if (is_global_default_ctx) {
> > > -			if (WARN_ON(dev_priv->mm.aliasing_ppgtt)) {
> > > -				ret = -EEXIST;
> > > -				goto err_unpin;
> > > -			}
> > > -
> > > -			dev_priv->mm.aliasing_ppgtt = ppgtt;
> > > -		}
> >
> > I expect some problems with full ppgtt & this (in some places, the
> > driver is still making some decisions based on
> > dev_priv->mm.aliasing_ppgtt, which now will be null).  Should I address
> > these problems in a subsequent patch?
> 
> Oh, good catch. I've done a bit a review and found two cases:
> - Driver unload code. Already fairly broken, made much worse by my series
>   here. I've fixed that up yesterday and will resend the series with those
>   additional patches and revised patches.
> - cmd parser. I guess that should be a fixup patch on top. I'll also do
>   that.
> 
> Have you spotted any other places?
The other place is gen8_ring_dispatch_execbuffer, it won't set the ppgtt
flag in MI_BATCH_BUFFER_START.

> 
> Thanks, Daniel
> 
> >
> > >  	} else if (USES_PPGTT(dev)) {
> > >  		/* For platforms which only have aliasing PPGTT, we fake the
> > >  		 * address space and refcounting. */
> > > @@ -361,7 +350,7 @@ int i915_gem_context_init(struct drm_device
> *dev)
> > >  		}
> > >  	}
> > >
> > > -	ctx = i915_gem_create_context(dev, NULL, USES_PPGTT(dev));
> > > +	ctx = i915_gem_create_context(dev, NULL,
> > > USES_FULL_PPGTT(dev));
> > >  	if (IS_ERR(ctx)) {
> > >  		DRM_ERROR("Failed to create default global context (error
> > > %ld)\n",
> > >  			  PTR_ERR(ctx));
> > >  }
> > >
> > > --
> > > 1.9.3
> >
> 
> 
> 
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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