Re: [PATCH] drm/i915: Stop discarding GTT cache-domain on unbind vma

From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org, Akash Goel <akash.goel@intel.com>
Subject: Re: [PATCH] drm/i915: Stop discarding GTT cache-domain on unbind vma
Date: Mon, 4 May 2015 16:14:41 +0200	[thread overview]
Message-ID: <20150504141441.GF30184@phenom.ffwll.local> (raw)
In-Reply-To: <1429790077-7412-1-git-send-email-chris@chris-wilson.co.uk>

On Thu, Apr 23, 2015 at 12:54:37PM +0100, Chris Wilson wrote:
> Since
> 
> commit 43566dedde54f9729113f5f9fde77d53e75e61e9
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date:   Fri Jan 2 16:29:29 2015 +0530
> 
>     drm/i915: Broaden application of set-domain(GTT)
> 
> we allowed objects to be in the GTT domain, but unbound. Therefore
> removing the GTT cache domain when removing the GGTT vma is no longer
> semantically correct.
> 
> An unfortunate side-effect is we lose the wondrously named
> i915_gem_object_finish_gtt(), not to be confused with
> i915_gem_gtt_finish_object()!

What are we going to do without that bit of hilarity ...
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Akash Goel <akash.goel@intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Queued for -next (with the rebase conflict resolved because I don't have
your tree), thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem.c | 22 +++-------------------
>  1 file changed, 3 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 6ffc4a619849..1ea94aec41d1 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3171,23 +3171,6 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
>  	return 0;
>  }
>  
> -static void i915_gem_object_finish_gtt(struct drm_i915_gem_object *obj)
> -{
> -	/* Force a pagefault for domain tracking on next user access */
> -	i915_gem_release_mmap(obj);
> -
> -	if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
> -		return;
> -
> -	/* Wait for any direct GTT access to complete */
> -	mb();
> -
> -	obj->base.read_domains &= ~I915_GEM_DOMAIN_GTT;
> -	obj->base.write_domain &= ~I915_GEM_DOMAIN_GTT;
> -
> -	trace_i915_gem_object_change_domain(obj);
> -}
> -
>  int i915_vma_unbind(struct i915_vma *vma)
>  {
>  	struct drm_i915_gem_object *obj = vma->obj;
> @@ -3219,12 +3202,13 @@ int i915_vma_unbind(struct i915_vma *vma)
>  	 */
>  
>  	if (vma->is_ggtt && vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) {
> -		i915_gem_object_finish_gtt(obj);
> -
>  		/* release the fence reg _after_ flushing */
>  		ret = i915_gem_object_put_fence(obj);
>  		if (ret)
>  			return ret;
> +
> +		/* Force a pagefault for domain tracking on next user access */
> +		i915_gem_release_mmap(obj);
>  	}
>  
>  	trace_i915_vma_unbind(vma);
> -- 
> 2.1.4
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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