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 <ch...@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

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