Re: [PATCH 2/2] drm/i915: Remove open-coded callers of flush_cpu_write_domain

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jan 21, 2015 at 02:53:49PM +0100, Daniel Vetter wrote:
> Both places check the cpu domain and through some indirection
> obj->pin_display and whether cpu access is coherent. And then flush
> both cpu caches and the chipset cache. Which is what
> flush_cpu_write_domain does.
> 
> Only difference is that on top we get a tracepoint, frontbuffer
> tracking and and domain tracking updates. Which doesn't matter since
> both paths are slowpaths.
> 
> So lets go with more shared code for clearer idioms.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 15 ++++-----------
>  1 file changed, 4 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 783d1040bf83..b48c39230b80 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1019,11 +1019,8 @@ out:
>  		 * cachelines in-line while writing and the object moved
>  		 * out of the cpu write domain while we've dropped the lock.
>  		 */
> -		if (!needs_clflush_after &&
> -		    obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
> -			if (i915_gem_clflush_object(obj, obj->pin_display))
> -				i915_gem_chipset_flush(dev);
> -		}
> +		if (!needs_clflush_after)
> +			i915_gem_object_flush_cpu_write_domain(obj);

Nack. You've just inverted the write domain check.

>  	}
>  
>  	if (needs_clflush_after)
> @@ -3825,12 +3822,8 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
>  		vma->node.color = cache_level;
>  	obj->cache_level = cache_level;
>  
> -	if (obj->cache_dirty &&
> -	    obj->base.write_domain != I915_GEM_DOMAIN_CPU &&
> -	    cpu_write_needs_clflush(obj)) {
> -		if (i915_gem_clflush_object(obj, true))
> -			i915_gem_chipset_flush(obj->base.dev);
> -	}
> +	if (obj->cache_dirty)
> +		i915_gem_object_flush_cpu_write_domain(obj);
>  
>  	return 0;
>  }
> -- 
> 2.1.4

-- 
Ville Syrjälä
Intel OTC
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