[Intel-gfx] [PATCH 1/3] drm/i915: Use consistent forcewake auto-release timeout across kernel configs

[Tvrtko Ursulin]

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

Current implementation releases the forcewake at any time between
straight away, and one jiffie from the last put, or first automatic
grab.

This does not sound like what was desired since jiffies are typically
between 1 and 10ms depending on the kernel configuration.

Change the auto-release mechanism to use hrtimers and set the timeout
to 1ms with a 1ms of slack. This should make the GPU power consistent
across kernel configs and the slack should enable some timer coallescing
where multiple force-wake domains exist, or with unrelated timers.

For GlBench/T-Rex this decreases the number of forcewake releases from
~480 to ~300 per second, and for a heavy combined OGL/OCL test from
~670 to ~360.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h     |  2 +-
 drivers/gpu/drm/i915/intel_uncore.c | 25 ++++++++++++++++---------
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index dd187727c813..7d4c704d7d75 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -666,7 +666,7 @@ struct intel_uncore {
 		struct drm_i915_private *i915;
 		enum forcewake_domain_id id;
 		unsigned wake_count;
-		struct timer_list timer;
+		struct hrtimer timer;
 		i915_reg_t reg_set;
 		u32 val_set;
 		u32 val_clear;
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index ac1c545436af..76ac990de354 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -60,7 +60,11 @@ fw_domain_reset(const struct intel_uncore_forcewake_domain *d)
 static inline void
 fw_domain_arm_timer(struct intel_uncore_forcewake_domain *d)
 {
-	mod_timer_pinned(&d->timer, jiffies + 1);
+	d->wake_count++;
+	hrtimer_start_range_ns(&d->timer,
+			       ktime_set(0, NSEC_PER_MSEC),
+			       NSEC_PER_MSEC,
+			       HRTIMER_MODE_REL);
 }
 
 static inline void
@@ -224,9 +228,11 @@ static int __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
 	return ret;
 }
 
-static void intel_uncore_fw_release_timer(unsigned long arg)
+static enum hrtimer_restart
+intel_uncore_fw_release_timer(struct hrtimer *timer)
 {
-	struct intel_uncore_forcewake_domain *domain = (void *)arg;
+	struct intel_uncore_forcewake_domain *domain =
+	       container_of(timer, struct intel_uncore_forcewake_domain, timer);
 	unsigned long irqflags;
 
 	assert_rpm_device_not_suspended(domain->i915);
@@ -240,6 +246,8 @@ static void intel_uncore_fw_release_timer(unsigned long arg)
 							  1 << domain->id);
 
 	spin_unlock_irqrestore(&domain->i915->uncore.lock, irqflags);
+
+	return HRTIMER_NORESTART;
 }
 
 void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
@@ -259,16 +267,16 @@ void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
 		active_domains = 0;
 
 		for_each_fw_domain(domain, dev_priv, id) {
-			if (del_timer_sync(&domain->timer) == 0)
+			if (hrtimer_cancel(&domain->timer) == 0)
 				continue;
 
-			intel_uncore_fw_release_timer((unsigned long)domain);
+			intel_uncore_fw_release_timer(&domain->timer);
 		}
 
 		spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
 
 		for_each_fw_domain(domain, dev_priv, id) {
-			if (timer_pending(&domain->timer))
+			if (hrtimer_active(&domain->timer))
 				active_domains |= (1 << id);
 		}
 
@@ -491,7 +499,6 @@ static void __intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
 		if (--domain->wake_count)
 			continue;
 
-		domain->wake_count++;
 		fw_domain_arm_timer(domain);
 	}
 }
@@ -732,7 +739,6 @@ static inline void __force_wake_auto(struct drm_i915_private *dev_priv,
 			continue;
 		}
 
-		domain->wake_count++;
 		fw_domain_arm_timer(domain);
 	}
 
@@ -1150,7 +1156,8 @@ static void fw_domain_init(struct drm_i915_private *dev_priv,
 	d->i915 = dev_priv;
 	d->id = domain_id;
 
-	setup_timer(&d->timer, intel_uncore_fw_release_timer, (unsigned long)d);
+	hrtimer_init(&d->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	d->timer.function = intel_uncore_fw_release_timer;
 
 	dev_priv->uncore.fw_domains |= (1 << domain_id);
 
-- 
1.9.1