On Wed, Apr 20, 2016 at 03:23:10PM +0100, Robert Bragg wrote:
> +static void i915_oa_stream_enable(struct i915_perf_stream *stream)
> +{
> + struct drm_i915_private *dev_priv = stream->dev_priv;
> +
> + dev_priv->perf.oa.ops.oa_enable(dev_priv);
> +
> + if (dev_priv->perf.oa.periodic)
> + hrtimer_start(&dev_priv->perf.oa.poll_check_timer,
> + ns_to_ktime(POLL_PERIOD),
> + HRTIMER_MODE_REL_PINNED);
> +}
> +static void i915_oa_stream_disable(struct i915_perf_stream *stream)
> +{
> + struct drm_i915_private *dev_priv = stream->dev_priv;
> +
> + dev_priv->perf.oa.ops.oa_disable(dev_priv);
> +
> + if (dev_priv->perf.oa.periodic)
> + hrtimer_cancel(&dev_priv->perf.oa.poll_check_timer);
> +}
> +static enum hrtimer_restart oa_poll_check_timer_cb(struct hrtimer *hrtimer)
> +{
> + struct drm_i915_private *dev_priv =
> + container_of(hrtimer, typeof(*dev_priv),
> + perf.oa.poll_check_timer);
> +
> + if (!dev_priv->perf.oa.ops.oa_buffer_is_empty(dev_priv))
> + wake_up(&dev_priv->perf.oa.poll_wq);
> +
> + hrtimer_forward_now(hrtimer, ns_to_ktime(POLL_PERIOD));
> +
> + return HRTIMER_RESTART;
> +}
> @@ -424,8 +1313,37 @@ void i915_perf_init(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = to_i915(dev);
>
> + if (!IS_HASWELL(dev))
> + return;
> +
> + hrtimer_init(&dev_priv->perf.oa.poll_check_timer,
> + CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + dev_priv->perf.oa.poll_check_timer.function = oa_poll_check_timer_cb;
> + init_waitqueue_head(&dev_priv->perf.oa.poll_wq);
This timer only serves to wake up pollers / wait_unlocked, right? So why
is it always running (when the stream is enabled)?
What happens to poll / wait_unlocked if oa.periodic is not set? It seems
like those functions would block indefinitely.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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