drm/i915/guc: Flush the residual log capture irq on disabling

As we disable the log capture events, flush any residual interrupt
before we flush and disable the worker.

v2: Mika pointed out that it wasn't the worker re-queueing itself, but a
rogue irq.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109716Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190221163833.21393-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_guc_log.c

@@ -620,7 +620,12 @@ void intel_guc_log_relay_flush(struct intel_guc_log *log)
 
 void intel_guc_log_relay_close(struct intel_guc_log *log)
 {
+	struct intel_guc *guc = log_to_guc(log);
+	struct drm_i915_private *i915 = guc_to_i915(guc);
+
 	guc_log_disable_flush_events(log);
+	synchronize_irq(i915->drm.irq);
+
 	flush_work(&log->relay.flush_work);
 
 	mutex_lock(&log->relay.lock);