3 files changed, 43 insertions, 18 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 759f523c6a6b..e741cd7f7fc6 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -60,6 +60,24 @@
  * and related files, but that will be described in separate chapters.
  */
 
+/*
+ * Interrupt statistic for PMU. Increments the counter only if the
+ * interrupt originated from the the GPU so interrupts from a device which
+ * shares the interrupt line are not accounted.
+ */
+static inline void pmu_irq_stats(struct drm_i915_private *i915,
+				 irqreturn_t res)
+{
+	if (unlikely(res != IRQ_HANDLED))
+		return;
+
+	/*
+	 * A clever compiler translates that into INC. A not so clever one
+	 * should at least prevent store tearing.
+	 */
+	WRITE_ONCE(i915->pmu.irq_count, i915->pmu.irq_count + 1);
+}
+
 typedef bool (*long_pulse_detect_func)(enum hpd_pin pin, u32 val);
 
 static const u32 hpd_ilk[HPD_NUM_PINS] = {
@@ -1599,6 +1617,8 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg)
 		valleyview_pipestat_irq_handler(dev_priv, pipe_stats);
 	} while (0);
 
+	pmu_irq_stats(dev_priv, ret);
+
 	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
 
 	return ret;
@@ -1676,6 +1696,8 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
 		valleyview_pipestat_irq_handler(dev_priv, pipe_stats);
 	} while (0);
 
+	pmu_irq_stats(dev_priv, ret);
+
 	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
 
 	return ret;
@@ -2103,6 +2125,8 @@ static irqreturn_t ilk_irq_handler(int irq, void *arg)
 	if (sde_ier)
 		raw_reg_write(regs, SDEIER, sde_ier);
 
+	pmu_irq_stats(i915, ret);
+
 	/* IRQs are synced during runtime_suspend, we don't require a wakeref */
 	enable_rpm_wakeref_asserts(&i915->runtime_pm);
 
@@ -2419,6 +2443,8 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
 
 	gen8_master_intr_enable(regs);
 
+	pmu_irq_stats(dev_priv, IRQ_HANDLED);
+
 	return IRQ_HANDLED;
 }
 
@@ -2514,6 +2540,8 @@ __gen11_irq_handler(struct drm_i915_private * const i915,
 
 	gen11_gu_misc_irq_handler(gt, gu_misc_iir);
 
+	pmu_irq_stats(i915, IRQ_HANDLED);
+
 	return IRQ_HANDLED;
 }
 
@@ -3688,6 +3716,8 @@ static irqreturn_t i8xx_irq_handler(int irq, void *arg)
 		i8xx_pipestat_irq_handler(dev_priv, iir, pipe_stats);
 	} while (0);
 
+	pmu_irq_stats(dev_priv, ret);
+
 	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
 
 	return ret;
@@ -3796,6 +3826,8 @@ static irqreturn_t i915_irq_handler(int irq, void *arg)
 		i915_pipestat_irq_handler(dev_priv, iir, pipe_stats);
 	} while (0);
 
+	pmu_irq_stats(dev_priv, ret);
+
 	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
 
 	return ret;
@@ -3941,6 +3973,8 @@ static irqreturn_t i965_irq_handler(int irq, void *arg)
 		i965_pipestat_irq_handler(dev_priv, iir, pipe_stats);
 	} while (0);
 
+	pmu_irq_stats(dev_priv, IRQ_HANDLED);
+
 	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
 
 	return ret;
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 69c0fa20eba1..3b88cb01b4da 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -4,7 +4,6 @@
  * Copyright © 2017-2018 Intel Corporation
  */
 
-#include <linux/irq.h>
 #include <linux/pm_runtime.h>
 
 #include "gt/intel_engine.h"
@@ -423,22 +422,6 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
 	return HRTIMER_RESTART;
 }
 
-static u64 count_interrupts(struct drm_i915_private *i915)
-{
-	/* open-coded kstat_irqs() */
-	struct irq_desc *desc = irq_to_desc(i915->drm.pdev->irq);
-	u64 sum = 0;
-	int cpu;
-
-	if (!desc || !desc->kstat_irqs)
-		return 0;
-
-	for_each_possible_cpu(cpu)
-		sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
-
-	return sum;
-}
-
 static void i915_pmu_event_destroy(struct perf_event *event)
 {
 	struct drm_i915_private *i915 =
@@ -581,7 +564,7 @@ static u64 __i915_pmu_event_read(struct perf_event *event)
 				   USEC_PER_SEC /* to MHz */);
 			break;
 		case I915_PMU_INTERRUPTS:
-			val = count_interrupts(i915);
+			val = READ_ONCE(pmu->irq_count);
 			break;
 		case I915_PMU_RC6_RESIDENCY:
 			val = get_rc6(&i915->gt);
diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h
index 941f0c14037c..9e49c6490780 100644
--- a/drivers/gpu/drm/i915/i915_pmu.h
+++ b/drivers/gpu/drm/i915/i915_pmu.h
@@ -108,6 +108,14 @@ struct i915_pmu {
 	 */
 	ktime_t sleep_last;
 	/**
+	 * @irq_count: Number of interrupts
+	 *
+	 * Intentionally unsigned long to avoid atomics or heuristics on 32bit.
+	 * 4e9 interrupts are a lot and postprocessing can really deal with an
+	 * occasional wraparound easily. It's 32bit after all.
+	 */
+	unsigned long irq_count;
+	/**
 	 * @events_attr_group: Device events attribute group.
 	 */
 	struct attribute_group events_attr_group;