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

[Daniel Vetter]

On Tue, Oct 06, 2015 at 01:02:22PM +0100, Chris Wilson wrote:
> Since
> 
> commit 43566dedde54f9729113f5f9fde77d53e75e61e9
> Author: Chris Wilson <chris at 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()!
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Akash Goel <akash.goel at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 20 +++-----------------
>  1 file changed, 3 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 8f498d4d874d..682af2ae3681 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3183,20 +3183,6 @@ 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;
> -
> -	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;
> @@ -3228,12 +3214,12 @@ 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);

Can't put_fence before release_mmap ... I guess we should have a testcase
for this somewhere? Hard to provoke probably ...
-Daniel

>  	}
>  
>  	if (!vma->vm->closed) {
> -- 
> 2.6.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch