[PATCH 5/5] drm/i915: Only grab and calculate timestamps when needed

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

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

Tiny cleanup to avoid grabbing a timestamp and calculating the
timeout when it is not going to be used. If anything makes the
profile correctly show busy wait spends time in get seqno and
not in ktime_get.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f1e3fdeea41f..d85c63dc36ac 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1199,7 +1199,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 		ACCESS_ONCE(dev_priv->gpu_error.test_irq_rings) & intel_ring_flag(ring);
 	DEFINE_WAIT(wait);
 	unsigned long timeout_expire;
-	s64 before, now;
+	s64 before;
 	int ret;
 
 	WARN(!intel_irqs_enabled(dev_priv), "IRQs disabled");
@@ -1210,15 +1210,17 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 	if (i915_gem_request_completed(req, true))
 		return 0;
 
-	timeout_expire = timeout ?
-		jiffies + nsecs_to_jiffies_timeout((u64)*timeout) : 0;
-
 	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();
+	if (timeout) {
+		before = ktime_get_raw_ns();
+		timeout_expire = jiffies + nsecs_to_jiffies_timeout((u64)*timeout);
+	} else {
+		timeout_expire = 0;
+	}
 
 	/* Optimistic spin for the next jiffie before touching IRQs */
 	ret = __i915_spin_request(req);
@@ -1284,11 +1286,10 @@ 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

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