Re: [RFC][PATCH 4/4] drm: i915: Atomic pageflip WIP

[Chris Wilson <chris@chris-wilson.co.uk>]

On Wed, 12 Sep 2012 18:47:07 +0300, ville.syrjala@linux.intel.com wrote:
> +static void intel_flip_finish(struct drm_flip *flip)
> +{
> +	struct intel_flip *intel_flip =
> +		container_of(flip, struct intel_flip, base);
> +	struct drm_device *dev = intel_flip->crtc->dev;
> +
> +	if (intel_flip->old_bo) {
> +		mutex_lock(&dev->struct_mutex);
> +
> +		intel_finish_fb(intel_flip->old_bo);

So if I understand correctly, this code is called after the flip is
already complete?

The intel_finish_fb() exists to flush pending batches and flips on the
current fb, prior to changing the scanout registers. (There is a
hardware dependency such that the GPU may be executing a command that
required the current modesetting.) In the case of flip completion, all
of those dependencies have already been retired and so the finish should
be a no-op. And so it should no be required, nor the changes to
intel_finish_fb (which should have included a change in the name to
indicate that is now taking the fb_obj).

> +		intel_unpin_fb_obj(intel_flip->old_bo);
> +
> +		mutex_unlock(&dev->struct_mutex);
> +	}
> +
> +}
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre