[Intel-gfx] [RFC v3] drm/i915: Android native sync support

[Chris Wilson]

On Tue, Jan 27, 2015 at 11:29:36AM +0000, Tvrtko Ursulin wrote:
> +static void i915_gem_request_unreference_worker(struct work_struct *work)
> +{
> +	struct drm_i915_gem_request *req =
> +		container_of(work, struct drm_i915_gem_request, unref_work);
> +	struct drm_device *dev = req->ring->dev;
> +
> +	mutex_lock(&dev->struct_mutex);
> +	i915_gem_request_unreference(req);
> +	mutex_unlock(&dev->struct_mutex);
> +}
> +
> +static int
> +i915_fence_ring_check(wait_queue_t *wait, unsigned mode, int flags, void *key)
> +{
> +	struct drm_i915_gem_request *req = wait->private;
> +	struct intel_engine_cs *ring = req->ring;
> +
> +	if (!i915_gem_request_completed(req, false))
> +		return 0;
> +
> +	fence_signal_locked(&req->fence);
> +
> +	__remove_wait_queue(&ring->irq_queue, wait);
> +	ring->irq_put(ring);
> +
> +	INIT_WORK(&req->unref_work, i915_gem_request_unreference_worker);
> +	schedule_work(&req->unref_work);
> +
> +	return 0;
> +}
> +
> +static bool i915_fence_ring_enable_signaling(struct fence *fence)
> +{
> +	struct drm_i915_gem_request *req = to_i915_request(fence);
> +	struct intel_engine_cs *ring = req->ring;
> +	struct drm_i915_private *dev_priv = ring->dev->dev_private;
> +	wait_queue_t *wait = &req->wait;
> +
> +	/* queue fence wait queue on irq queue and get fence */
> +	if (i915_gem_request_completed(req, false) ||
> +	    i915_terminally_wedged(&dev_priv->gpu_error))
> +		return false;
> +
> +	if (!ring->irq_get(ring))
> +		return false;
> +
> +	if (i915_gem_request_completed(req, false)) {
> +		ring->irq_put(ring);
> +		return true;
> +	}
> +
> +	wait->flags = 0;
> +	wait->private = req;
> +	wait->func = i915_fence_ring_check;
> +
> +	i915_gem_request_reference(req);
> +
> +	__add_wait_queue(&ring->irq_queue, wait);
> +
> +	return true;
> +}

Explain how fence_release interacts with enable_signalling. Presumably
either the core fence routines cleanup the outstanding signalling, or we
are expected to. Doing so will remove the requirement for the extra
ref/unref (including the worker).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre