drm/i915: Track GT interrupt handling using the master iir

Keep the master iir and use it to reduce the number of reads and writes
to the GT iir array, i.e. only the bits marked as set by the master iir
are valid inside GT iir array and will be handled during the interrupt.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180215073713.26985-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_irq.c

@@ -1416,6 +1416,14 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir, int test_shift)
 static void gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
 			    u32 master_ctl, u32 gt_iir[4])
 {
+#define GEN8_GT_IRQS (GEN8_GT_RCS_IRQ | \
+		      GEN8_GT_BCS_IRQ | \
+		      GEN8_GT_VCS1_IRQ | \
+		      GEN8_GT_VCS2_IRQ | \
+		      GEN8_GT_VECS_IRQ | \
+		      GEN8_GT_PM_IRQ | \
+		      GEN8_GT_GUC_IRQ)
+
 	if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
 		gt_iir[0] = I915_READ_FW(GEN8_GT_IIR(0));
 		if (gt_iir[0])
@@ -1446,31 +1454,34 @@ static void gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
 }
 
 static void gen8_gt_irq_handler(struct drm_i915_private *dev_priv,
-				u32 gt_iir[4])
+				u32 master_ctl, u32 gt_iir[4])
 {
-	if (gt_iir[0]) {
+	if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
 		gen8_cs_irq_handler(dev_priv->engine[RCS],
 				    gt_iir[0], GEN8_RCS_IRQ_SHIFT);
 		gen8_cs_irq_handler(dev_priv->engine[BCS],
 				    gt_iir[0], GEN8_BCS_IRQ_SHIFT);
 	}
 
-	if (gt_iir[1]) {
+	if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
 		gen8_cs_irq_handler(dev_priv->engine[VCS],
 				    gt_iir[1], GEN8_VCS1_IRQ_SHIFT);
 		gen8_cs_irq_handler(dev_priv->engine[VCS2],
 				    gt_iir[1], GEN8_VCS2_IRQ_SHIFT);
 	}
 
-	if (gt_iir[3])
+	if (master_ctl & GEN8_GT_VECS_IRQ) {
 		gen8_cs_irq_handler(dev_priv->engine[VECS],
 				    gt_iir[3], GEN8_VECS_IRQ_SHIFT);
+	}
 
+	if (master_ctl & (GEN8_GT_PM_IRQ | GEN8_GT_GUC_IRQ)) {
 		if (gt_iir[2] & dev_priv->pm_rps_events)
 			gen6_rps_irq_handler(dev_priv, gt_iir[2]);
 
 		if (gt_iir[2] & dev_priv->pm_guc_events)
 			gen9_guc_irq_handler(dev_priv, gt_iir[2]);
+	}
 }
 
 static bool bxt_port_hotplug_long_detect(enum port port, u32 val)
@@ -2085,9 +2096,9 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
 
 	do {
 		u32 master_ctl, iir;
-		u32 gt_iir[4] = {};
 		u32 pipe_stats[I915_MAX_PIPES] = {};
 		u32 hotplug_status = 0;
+		u32 gt_iir[4];
 		u32 ier = 0;
 
 		master_ctl = I915_READ(GEN8_MASTER_IRQ) & ~GEN8_MASTER_IRQ_CONTROL;
@@ -2140,7 +2151,7 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
 		I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
 		POSTING_READ(GEN8_MASTER_IRQ);
 
-		gen8_gt_irq_handler(dev_priv, gt_iir);
+		gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir);
 
 		if (hotplug_status)
 			i9xx_hpd_irq_handler(dev_priv, hotplug_status);
@@ -2675,10 +2686,9 @@ gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
 
 static irqreturn_t gen8_irq_handler(int irq, void *arg)
 {
-	struct drm_device *dev = arg;
-	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_i915_private *dev_priv = to_i915(arg);
 	u32 master_ctl;
-	u32 gt_iir[4] = {};
+	u32 gt_iir[4];
 
 	if (!intel_irqs_enabled(dev_priv))
 		return IRQ_NONE;
@@ -2690,18 +2700,19 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
 
 	I915_WRITE_FW(GEN8_MASTER_IRQ, 0);
 
-	/* IRQs are synced during runtime_suspend, we don't require a wakeref */
-	disable_rpm_wakeref_asserts(dev_priv);
-
 	/* Find, clear, then process each source of interrupt */
 	gen8_gt_irq_ack(dev_priv, master_ctl, gt_iir);
-	gen8_gt_irq_handler(dev_priv, gt_iir);
+
+	/* IRQs are synced during runtime_suspend, we don't require a wakeref */
+	if (master_ctl & ~GEN8_GT_IRQS) {
+		disable_rpm_wakeref_asserts(dev_priv);
 		gen8_de_irq_handler(dev_priv, master_ctl);
+		enable_rpm_wakeref_asserts(dev_priv);
+	}
 
 	I915_WRITE_FW(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
-	POSTING_READ_FW(GEN8_MASTER_IRQ);
 
-	enable_rpm_wakeref_asserts(dev_priv);
+	gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir);
 
 	return IRQ_HANDLED;
 }