drm/i915: Prune gen8_gt_irq_handler

The compiler is not automatically caching the i915->regs address inside
a register and emitting a load for every mmio access. For simple
functions like gen8_gt_irq_handler that are already using the raw
accessors, we can open-code them for substantial savings:

add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-83 (-83)
Function                                     old     new   delta
gen8_gt_irq_handler                          290     266     -24
gen8_gt_irq_ack                              181     122     -59
Total: Before=954637, After=954554, chg -0.01%

v2: Add raw_reg_read/raw_reg_write.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180219100926.16554-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_irq.c

@@ -1413,9 +1413,11 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir, int test_shift)
 		tasklet_hi_schedule(&execlists->tasklet);
 }
 
-static void gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
+static void gen8_gt_irq_ack(struct drm_i915_private *i915,
 			    u32 master_ctl, u32 gt_iir[4])
 {
+	void __iomem * const regs = i915->regs;
+
 #define GEN8_GT_IRQS (GEN8_GT_RCS_IRQ | \
 		      GEN8_GT_BCS_IRQ | \
 		      GEN8_GT_VCS1_IRQ | \
@@ -1425,62 +1427,58 @@ static void gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
 		      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])
-			I915_WRITE_FW(GEN8_GT_IIR(0), gt_iir[0]);
+		gt_iir[0] = raw_reg_read(regs, GEN8_GT_IIR(0));
+		if (likely(gt_iir[0]))
+			raw_reg_write(regs, GEN8_GT_IIR(0), gt_iir[0]);
 	}
 
 	if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
-		gt_iir[1] = I915_READ_FW(GEN8_GT_IIR(1));
-		if (gt_iir[1])
-			I915_WRITE_FW(GEN8_GT_IIR(1), gt_iir[1]);
+		gt_iir[1] = raw_reg_read(regs, GEN8_GT_IIR(1));
+		if (likely(gt_iir[1]))
+			raw_reg_write(regs, GEN8_GT_IIR(1), gt_iir[1]);
 	}
 
-	if (master_ctl & GEN8_GT_VECS_IRQ) {
-		gt_iir[3] = I915_READ_FW(GEN8_GT_IIR(3));
-		if (gt_iir[3])
-			I915_WRITE_FW(GEN8_GT_IIR(3), gt_iir[3]);
+	if (master_ctl & (GEN8_GT_PM_IRQ | GEN8_GT_GUC_IRQ)) {
+		gt_iir[2] = raw_reg_read(regs, GEN8_GT_IIR(2));
+		if (likely(gt_iir[2] & (i915->pm_rps_events |
+					i915->pm_guc_events)))
+			raw_reg_write(regs, GEN8_GT_IIR(2),
+				      gt_iir[2] & (i915->pm_rps_events |
+						   i915->pm_guc_events));
 	}
 
-	if (master_ctl & (GEN8_GT_PM_IRQ | GEN8_GT_GUC_IRQ)) {
-		gt_iir[2] = I915_READ_FW(GEN8_GT_IIR(2));
-		if (gt_iir[2] & (dev_priv->pm_rps_events |
-				 dev_priv->pm_guc_events)) {
-			I915_WRITE_FW(GEN8_GT_IIR(2),
-				      gt_iir[2] & (dev_priv->pm_rps_events |
-						   dev_priv->pm_guc_events));
-		}
+	if (master_ctl & GEN8_GT_VECS_IRQ) {
+		gt_iir[3] = raw_reg_read(regs, GEN8_GT_IIR(3));
+		if (likely(gt_iir[3]))
+			raw_reg_write(regs, GEN8_GT_IIR(3), gt_iir[3]);
 	}
 }
 
-static void gen8_gt_irq_handler(struct drm_i915_private *dev_priv,
+static void gen8_gt_irq_handler(struct drm_i915_private *i915,
 				u32 master_ctl, u32 gt_iir[4])
 {
 	if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
-		gen8_cs_irq_handler(dev_priv->engine[RCS],
+		gen8_cs_irq_handler(i915->engine[RCS],
 				    gt_iir[0], GEN8_RCS_IRQ_SHIFT);
-		gen8_cs_irq_handler(dev_priv->engine[BCS],
+		gen8_cs_irq_handler(i915->engine[BCS],
 				    gt_iir[0], GEN8_BCS_IRQ_SHIFT);
 	}
 
 	if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
-		gen8_cs_irq_handler(dev_priv->engine[VCS],
+		gen8_cs_irq_handler(i915->engine[VCS],
 				    gt_iir[1], GEN8_VCS1_IRQ_SHIFT);
-		gen8_cs_irq_handler(dev_priv->engine[VCS2],
+		gen8_cs_irq_handler(i915->engine[VCS2],
 				    gt_iir[1], GEN8_VCS2_IRQ_SHIFT);
 	}
 
 	if (master_ctl & GEN8_GT_VECS_IRQ) {
-		gen8_cs_irq_handler(dev_priv->engine[VECS],
+		gen8_cs_irq_handler(i915->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]);
+		gen6_rps_irq_handler(i915, gt_iir[2]);
+		gen9_guc_irq_handler(i915, gt_iir[2]);
 	}
 }
 

drivers/gpu/drm/i915/intel_uncore.h

@@ -186,4 +186,9 @@ int intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
 					    2, timeout_ms, NULL);
 }
 
+#define raw_reg_read(base, reg) \
+	readl(base + i915_mmio_reg_offset(reg))
+#define raw_reg_write(base, reg, value) \
+	writel(value, base + i915_mmio_reg_offset(reg))
+
 #endif /* !__INTEL_UNCORE_H__ */