[Intel-gfx] [PATCH] drm/i915: Show support for accurate sw PMU busyness tracking

[Chris Wilson]

Expose whether or not we support the PMU software tracking in our
scheduler capabilities, so userspace can query at runtime.

v2: Use I915_SCHEDULER_CAP_ENGINE_BUSY_STATS for a less ambiguous
capability name.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
For reference, Tvrtko suggested an alternative back in Feb,
"I am leaning towards thinking PMU is a backend and not the scheduler
feature. We could export it via engine discovery for instance."
-Chris
---
 drivers/gpu/drm/i915/gt/intel_engine_cs.c | 7 ++++---
 drivers/gpu/drm/i915/i915_pmu.c           | 4 +---
 include/uapi/drm/i915_drm.h               | 1 +
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index c1fb5fa3952e..7d6d6e62e9cc 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -688,9 +688,10 @@ void intel_engines_set_scheduler_caps(struct drm_i915_private *i915)
 		u8 engine;
 		u8 sched;
 	} map[] = {
-#define MAP(x, y) { ilog2(I915_ENGINE_HAS_##x), ilog2(I915_SCHEDULER_CAP_##y) }
-		MAP(PREEMPTION, PREEMPTION),
-		MAP(SEMAPHORES, SEMAPHORES),
+#define MAP(x, y) { ilog2(I915_ENGINE_##x), ilog2(I915_SCHEDULER_CAP_##y) }
+		MAP(HAS_PREEMPTION, PREEMPTION),
+		MAP(HAS_SEMAPHORES, SEMAPHORES),
+		MAP(SUPPORTS_STATS, ENGINE_BUSY_STATS),
 #undef MAP
 	};
 	struct intel_engine_cs *engine;
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 8fe46ee920a0..eff86483bec0 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -102,10 +102,8 @@ static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
 	/*
 	 * Also there is software busyness tracking available we do not
 	 * need the timer for I915_SAMPLE_BUSY counter.
-	 *
-	 * Use RCS as proxy for all engines.
 	 */
-	else if (intel_engine_supports_stats(i915->engine[RCS0]))
+	else if (i915->caps.scheduler & I915_SCHEDULER_CAP_ENGINE_BUSY_STATS)
 		enable &= ~BIT(I915_SAMPLE_BUSY);
 
 	/*
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 328d05e77d9f..469dc512cca3 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -521,6 +521,7 @@ typedef struct drm_i915_irq_wait {
 #define   I915_SCHEDULER_CAP_PRIORITY	(1ul << 1)
 #define   I915_SCHEDULER_CAP_PREEMPTION	(1ul << 2)
 #define   I915_SCHEDULER_CAP_SEMAPHORES	(1ul << 3)
+#define   I915_SCHEDULER_CAP_ENGINE_BUSY_STATS	(1ul << 4)
 
 #define I915_PARAM_HUC_STATUS		 42
 
-- 
2.20.1