[Intel-gfx] [PATCH 25/38] drm/i915/pmu: Always sample an active ringbuffer

[Chris Wilson]

As we no longer have a precise indication of requests queued to an
engine, make no presumptions and just sample the ring registers to see
if the engine is busy.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_pmu.c | 47 +++++++++++----------------------
 1 file changed, 16 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index b1cb2d3cae16..452589a7e473 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -148,14 +148,6 @@ void i915_pmu_gt_unparked(struct drm_i915_private *i915)
 	spin_unlock_irq(&i915->pmu.lock);
 }
 
-static bool grab_forcewake(struct drm_i915_private *i915, bool fw)
-{
-	if (!fw)
-		intel_uncore_forcewake_get(i915, FORCEWAKE_ALL);
-
-	return true;
-}
-
 static void
 add_sample(struct i915_pmu_sample *sample, u32 val)
 {
@@ -168,7 +160,6 @@ engines_sample(struct drm_i915_private *dev_priv, unsigned int period_ns)
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 	intel_wakeref_t wakeref;
-	bool fw = false;
 
 	if ((dev_priv->pmu.enable & ENGINE_SAMPLE_MASK) == 0)
 		return;
@@ -180,37 +171,31 @@ engines_sample(struct drm_i915_private *dev_priv, unsigned int period_ns)
 	if (!wakeref)
 		return;
 
+	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
 	for_each_engine(engine, dev_priv, id) {
-		u32 current_seqno = intel_engine_get_seqno(engine);
-		u32 last_seqno = intel_engine_last_submit(engine);
+		typeof(engine->pmu) *pmu = &engine->pmu;
 		u32 val;
 
-		val = !i915_seqno_passed(current_seqno, last_seqno);
-
-		if (val)
-			add_sample(&engine->pmu.sample[I915_SAMPLE_BUSY],
-				   period_ns);
+		val = I915_READ_FW(RING_MI_MODE(engine->mmio_base));
+		if (val & MODE_IDLE)
+			continue;
 
-		if (val && (engine->pmu.enable &
-		    (BIT(I915_SAMPLE_WAIT) | BIT(I915_SAMPLE_SEMA)))) {
-			fw = grab_forcewake(dev_priv, fw);
+		add_sample(&pmu->sample[I915_SAMPLE_BUSY], period_ns);
 
+		if (pmu->enable &
+		    (BIT(I915_SAMPLE_WAIT) | BIT(I915_SAMPLE_SEMA))) {
 			val = I915_READ_FW(RING_CTL(engine->mmio_base));
-		} else {
-			val = 0;
-		}
 
-		if (val & RING_WAIT)
-			add_sample(&engine->pmu.sample[I915_SAMPLE_WAIT],
-				   period_ns);
+			if (val & RING_WAIT)
+				add_sample(&pmu->sample[I915_SAMPLE_WAIT],
+					   period_ns);
 
-		if (val & RING_WAIT_SEMAPHORE)
-			add_sample(&engine->pmu.sample[I915_SAMPLE_SEMA],
-				   period_ns);
+			if (val & RING_WAIT_SEMAPHORE)
+				add_sample(&pmu->sample[I915_SAMPLE_SEMA],
+					   period_ns);
+		}
 	}
-
-	if (fw)
-		intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
 
 	intel_runtime_pm_put(dev_priv, wakeref);
 }
-- 
2.20.1