[PATCH v6 4/5] drm/i915: Implement end_cpu_access

[Chris Wilson]

On Wed, Dec 16, 2015 at 08:25:36PM -0200, Tiago Vignatti wrote:
> This function is meant to be used with dma-buf mmap, when finishing the CPU
> access of the mapped pointer.
> 
> +static void i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
> +{
> +	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
> +	struct drm_device *dev = obj->base.dev;
> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +	bool was_interruptible, write = (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE);
> +	int ret;
> +
> +	mutex_lock(&dev->struct_mutex);
> +	was_interruptible = dev_priv->mm.interruptible;
> +	dev_priv->mm.interruptible = false;
> +
> +	ret = i915_gem_object_set_to_gtt_domain(obj, write);

This only needs to pass .write=false. The dma-buf direction is
only for the period of the user access, and we are now flushing the
caches. This is equivalent to the sw-finish ioctl and ideally we just
want the i915_gem_object_flush_cpu_write_domain().
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre