[Intel-gfx] [PATCH] i915/guc: Run busyness worker only if gt is awake

[Umesh Nerlige Ramappa]

The worker is canceled in the __gt_park path, but we still see it
running sometimes during suspend.

Only update stats if gt is awake. If not, intel_guc_busyness_park would
have already updated the stats. Note that we do not requeue the worker
if gt is not awake since intel_guc_busyness_unpark would do that at some
point.

If the gt was parked longer than time taken for GT timestamp to roll
over, we ignore those rollovers since we don't care about tracking the
exact GT time. We only care about roll overs when the gt is active and
running workloads.

v2 (Daniele)
- Edit commit message and code comment
- Use runtime pm in the worker
- Put runtime pm after enabling the worker
- Use Link tag and add Fixes tag

Link: https://gitlab.freedesktop.org/drm/intel/-/issues/7077
Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu")
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 26 ++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index e250bedf90fb..d37b255559a0 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1461,6 +1461,24 @@ static void guc_timestamp_ping(struct work_struct *wrk)
 	unsigned long index;
 	int srcu, ret;
 
+	/*
+	 * The worker is canceled in the __gt_park path, but we still see it
+	 * running sometimes during suspend.
+	 *
+	 * Only update stats if gt is awake. If not, intel_guc_busyness_park
+	 * would have already updated the stats. Note that we do not requeue the
+	 * worker in this case since intel_guc_busyness_unpark would do that at
+	 * some point.
+	 *
+	 * If the gt was parked longer than time taken for GT timestamp to roll
+	 * over, we ignore those rollovers since we don't care about tracking
+	 * the exact GT time. We only care about roll overs when the gt is
+	 * active and running workloads.
+	 */
+	wakeref = intel_runtime_pm_get_if_active(&gt->i915->runtime_pm);
+	if (!wakeref)
+		return;
+
 	/*
 	 * Synchronize with gt reset to make sure the worker does not
 	 * corrupt the engine/guc stats. NB: can't actually block waiting
@@ -1469,10 +1487,9 @@ static void guc_timestamp_ping(struct work_struct *wrk)
 	 */
 	ret = intel_gt_reset_trylock(gt, &srcu);
 	if (ret)
-		return;
+		goto err_trylock;
 
-	with_intel_runtime_pm(&gt->i915->runtime_pm, wakeref)
-		__update_guc_busyness_stats(guc);
+	__update_guc_busyness_stats(guc);
 
 	/* adjust context stats for overflow */
 	xa_for_each(&guc->context_lookup, index, ce)
@@ -1481,6 +1498,9 @@ static void guc_timestamp_ping(struct work_struct *wrk)
 	intel_gt_reset_unlock(gt, srcu);
 
 	guc_enable_busyness_worker(guc);
+
+err_trylock:
+	intel_runtime_pm_put(&gt->i915->runtime_pm, wakeref);
 }
 
 static int guc_action_enable_usage_stats(struct intel_guc *guc)
-- 
2.38.1