[Intel-gfx] [PATCH] drm/i915/pmu: Turn off the timer to sample frequencies when GT is parked

[Ashutosh Dixit]

pmu_needs_timer() keeps the timer running even when GT is parked,
ostensibly to sample requested/actual frequencies. However
frequency_sample() has the following:

	/* Report 0/0 (actual/requested) frequency while parked. */
	if (!intel_gt_pm_get_if_awake(gt))
		return;

The above code prevents frequencies to be sampled while the GT is
parked. So we might as well turn off the sampling timer itself in this
case and save CPU cycles/power.

Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 7ece883a7d956..8db1d681cf4ab 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -124,11 +124,14 @@ static bool pmu_needs_timer(struct i915_pmu *pmu, bool gpu_active)
 		  ENGINE_SAMPLE_MASK;
 
 	/*
-	 * When the GPU is idle per-engine counters do not need to be
-	 * running so clear those bits out.
+	 * When GPU is idle, frequency or per-engine counters do not need
+	 * to be running so clear those bits out.
 	 */
-	if (!gpu_active)
-		enable &= ~ENGINE_SAMPLE_MASK;
+	if (!gpu_active) {
+		enable &= ~(config_mask(I915_PMU_ACTUAL_FREQUENCY) |
+			    config_mask(I915_PMU_REQUESTED_FREQUENCY) |
+			    ENGINE_SAMPLE_MASK);
+	}
 	/*
 	 * Also there is software busyness tracking available we do not
 	 * need the timer for I915_SAMPLE_BUSY counter.
-- 
2.38.0