[Intel-gfx] [RFC 5/7] drm/i915: Wait for GPU to finish before event stop in Gen Perf PMU

[Chris Wilson]

On Mon, Jun 22, 2015 at 03:25:07PM +0530, sourab.gupta at intel.com wrote:
> From: Sourab Gupta <sourab.gupta at intel.com>
> 
> To collect timestamps around any GPU workload, we need to insert
> commands to capture them into the ringbuffer. Therefore, during the stop event
> call, we need to wait for GPU to complete processing the last request for
> which these commands were inserted.
> We need to ensure this processing is done before event_destroy callback which
> deallocates the buffer for holding the data.

There's no reason for this to be synchronous. Just that you need an
active reference on the output buffer to be only released after the
final request.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre