[PATCH] pmu underrun test

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index dc87797db500..ef81257212df 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -237,14 +237,18 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
 {
 	struct drm_i915_private *i915 =
 		container_of(hrtimer, struct drm_i915_private, pmu.timer);
+	ktime_t now;
 
 	if (!READ_ONCE(i915->pmu.timer_enabled))
 		return HRTIMER_NORESTART;
 
+	now = ktime_get();
+
 	engines_sample(i915);
 	frequency_sample(i915);
 
-	hrtimer_forward_now(hrtimer, ns_to_ktime(PERIOD));
+	WARN_ON(hrtimer_forward(hrtimer, now, ns_to_ktime(PERIOD)));
+
 	return HRTIMER_RESTART;
 }
 
-- 
2.17.0