metag, perf: Use common PMU interrupt disabled code

Transition to using the new generic PERF_PMU_CAP_NO_INTERRUPT method for
failing a sampling event when no PMU interrupt is available.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Acked-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linux-metag@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1406150202050.16738@vincent-weaver-1.umelst.maine.edu
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/metag/kernel/perf/perf_event.c

@@ -567,16 +567,6 @@ static int _hw_perf_event_init(struct perf_event *event)
 	if (mapping == -1)
 		return -EINVAL;
 
-	/*
-	 * Early cores have "limited" counters - they have no overflow
-	 * interrupts - and so are unable to do sampling without extra work
-	 * and timer assistance.
-	 */
-	if (metag_pmu->max_period == 0) {
-		if (hwc->sample_period)
-			return -EINVAL;
-	}
-
 	/*
 	 * Don't assign an index until the event is placed into the hardware.
 	 * -1 signifies that we're still deciding where to put it. On SMP
@@ -866,6 +856,15 @@ static int __init init_hw_perf_events(void)
 	pr_info("enabled with %s PMU driver, %d counters available\n",
 			metag_pmu->name, metag_pmu->max_events);
 
+	/*
+	 * Early cores have "limited" counters - they have no overflow
+	 * interrupts - and so are unable to do sampling without extra work
+	 * and timer assistance.
+	 */
+	if (metag_pmu->max_period == 0) {
+		metag_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+	}
+
 	/* Initialise the active events and reservation mutex */
 	atomic_set(&metag_pmu->active_events, 0);
 	mutex_init(&metag_pmu->reserve_mutex);