drm/i915: Convert the register access tracepoint to be conditional

The TRACE_EVENT_CONDITION is supposed to generate more efficient code
than if (cond) trace(), which is what we are currently using inside the
register access functions.

v2: Rebase onto uncore
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1004,7 +1004,7 @@ static int gen6_drpc_info(struct seq_file *m)
 	}
 
 	gt_core_status = readl(dev_priv->regs + GEN6_GT_CORE_STATUS);
-	trace_i915_reg_rw(false, GEN6_GT_CORE_STATUS, gt_core_status, 4);
+	trace_i915_reg_rw(false, GEN6_GT_CORE_STATUS, gt_core_status, 4, true);
 
 	rpmodectl1 = I915_READ(GEN6_RP_CONTROL);
 	rcctl1 = I915_READ(GEN6_RC_CONTROL);

drivers/gpu/drm/i915/i915_trace.h

@@ -406,10 +406,12 @@ TRACE_EVENT(i915_flip_complete,
 	    TP_printk("plane=%d, obj=%p", __entry->plane, __entry->obj)
 );
 
-TRACE_EVENT(i915_reg_rw,
-	TP_PROTO(bool write, u32 reg, u64 val, int len),
+TRACE_EVENT_CONDITION(i915_reg_rw,
+	TP_PROTO(bool write, u32 reg, u64 val, int len, bool trace),
 
-	TP_ARGS(write, reg, val, len),
+	TP_ARGS(write, reg, val, len, trace),
+
+	TP_CONDITION(trace),
 
 	TP_STRUCT__entry(
 		__field(u64, val)

drivers/gpu/drm/i915/intel_uncore.c

@@ -359,7 +359,7 @@ u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg, bool trace) { \
 		val = __raw_i915_read##x(dev_priv, reg); \
 	} \
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); \
-	if (trace) trace_i915_reg_rw(false, reg, val, sizeof(val)); \
+	trace_i915_reg_rw(false, reg, val, sizeof(val), trace); \
 	return val; \
 }
 
@@ -373,7 +373,7 @@ __i915_read(64)
 void i915_write##x(struct drm_i915_private *dev_priv, u32 reg, u##x val, bool trace) { \
 	unsigned long irqflags; \
 	u32 __fifo_ret = 0; \
-	if (trace) trace_i915_reg_rw(true, reg, val, sizeof(val)); \
+	trace_i915_reg_rw(true, reg, val, sizeof(val), trace); \
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags); \
 	if (NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
 		__fifo_ret = __gen6_gt_wait_for_fifo(dev_priv); \