[Intel-gfx] [PATCH 6/6] drm/i915: Only grab timestamps when needed

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

No need to call ktime_get_raw_ns twice per unlimited wait and can
also elimate a local variable.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index de98dc41fb9f..c4f69579eb7a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1246,7 +1246,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 	int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
 	DEFINE_WAIT(wait);
 	unsigned long timeout_expire;
-	s64 before, now;
+	s64 before = 0;
 	int ret;
 
 	WARN(!intel_irqs_enabled(dev_priv), "IRQs disabled");
@@ -1266,14 +1266,17 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 			return -ETIME;
 
 		timeout_expire = jiffies + nsecs_to_jiffies_timeout(*timeout);
+
+		/*
+		 * Record current time in case interrupted by signal, or wedged.
+		 */
+		before = ktime_get_raw_ns();
 	}
 
 	if (INTEL_INFO(dev_priv)->gen >= 6)
 		gen6_rps_boost(dev_priv, rps, req->emitted_jiffies);
 
-	/* Record current time in case interrupted by signal, or wedged */
 	trace_i915_gem_request_wait_begin(req);
-	before = ktime_get_raw_ns();
 
 	/* Optimistic spin for the next jiffie before touching IRQs */
 	ret = __i915_spin_request(req, state);
@@ -1331,11 +1334,10 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 	finish_wait(&ring->irq_queue, &wait);
 
 out:
-	now = ktime_get_raw_ns();
 	trace_i915_gem_request_wait_end(req);
 
 	if (timeout) {
-		s64 tres = *timeout - (now - before);
+		s64 tres = *timeout - (ktime_get_raw_ns() - before);
 
 		*timeout = tres < 0 ? 0 : tres;
 
-- 
1.9.1