[PATCH 1/3] drm/i915: Trim gen8_irq_handler

[Chris Wilson]

The goal here is to trim an excess posting read and keep the predicates
tight (reusing the same predicate throughout for GT ack/handling).

add/remove: 0/0 grow/shrink: 2/1 up/down: 26/-30 (-4)
function                                     old     new   delta
gen8_gt_irq_handler                          282     301     +19
cherryview_irq_handler                       450     457      +7
gen8_irq_handler                            1653    1623     -30

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_irq.c | 54 +++++++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 91a2c5dbf2da..e12321cb7403 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1375,31 +1375,34 @@ static irqreturn_t 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 (gt_iir[2] & dev_priv->pm_rps_events)
-		gen6_rps_irq_handler(dev_priv, gt_iir[2]);
+	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]);
+		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)
@@ -1984,7 +1987,7 @@ 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);
@@ -2518,36 +2521,39 @@ gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
 	return ret;
 }
 
+#define GEN8_GT_IRQ_BITS (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)
+
 static irqreturn_t gen8_irq_handler(int irq, void *arg)
 {
-	struct drm_device *dev = arg;
-	struct drm_i915_private *dev_priv = to_i915(dev);
-	u32 master_ctl;
-	u32 gt_iir[4] = {};
-	irqreturn_t ret;
+	struct drm_i915_private *dev_priv = arg;
+	u32 master_ctl, gt_iir[4];
+	irqreturn_t ret = IRQ_NONE;
 
 	if (!intel_irqs_enabled(dev_priv))
 		return IRQ_NONE;
 
-	master_ctl = I915_READ_FW(GEN8_MASTER_IRQ);
-	master_ctl &= ~GEN8_MASTER_IRQ_CONTROL;
+	master_ctl = I915_READ_FW(GEN8_MASTER_IRQ) &  ~GEN8_MASTER_IRQ_CONTROL;
 	if (!master_ctl)
 		return IRQ_NONE;
 
 	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 */
-	ret = gen8_gt_irq_ack(dev_priv, master_ctl, gt_iir);
-	gen8_gt_irq_handler(dev_priv, gt_iir);
-	ret |= gen8_de_irq_handler(dev_priv, master_ctl);
+	if (master_ctl & GEN8_GT_IRQ_BITS)
+		ret |= gen8_gt_irq_ack(dev_priv, master_ctl, gt_iir);
+
+	if (master_ctl & ~GEN8_GT_IRQ_BITS) {
+		disable_rpm_wakeref_asserts(dev_priv);
+		ret |= 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);
+	if (master_ctl & GEN8_GT_IRQ_BITS)
+		gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir);
 
 	return ret;
 }
-- 
2.14.1