drm/i915: Reduce locking in execlist command submission

This eliminates six needless spin lock/unlock pairs when writing out
ELSP.

v2: Respin with my preferred colour.
v3: Mostly back to the original colour

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> [v1]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 76 insertions, 22 deletions

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index ab5cc94588e1..d96d15faf268 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -375,6 +375,26 @@ void intel_uncore_sanitize(struct drm_device *dev)
 	intel_disable_gt_powersave(dev);
 }
 
+static void __intel_uncore_forcewake_get(struct drm_i915_private *dev_priv,
+					 enum forcewake_domains fw_domains)
+{
+	struct intel_uncore_forcewake_domain *domain;
+	enum forcewake_domain_id id;
+
+	if (!dev_priv->uncore.funcs.force_wake_get)
+		return;
+
+	fw_domains &= dev_priv->uncore.fw_domains;
+
+	for_each_fw_domain_mask(domain, fw_domains, dev_priv, id) {
+		if (domain->wake_count++)
+			fw_domains &= ~(1 << id);
+	}
+
+	if (fw_domains)
+		dev_priv->uncore.funcs.force_wake_get(dev_priv, fw_domains);
+}
+
 /**
  * intel_uncore_forcewake_get - grab forcewake domain references
  * @dev_priv: i915 device instance
@@ -392,41 +412,39 @@ void intel_uncore_forcewake_get(struct drm_i915_private *dev_priv,
 				enum forcewake_domains fw_domains)
 {
 	unsigned long irqflags;
-	struct intel_uncore_forcewake_domain *domain;
-	enum forcewake_domain_id id;
 
 	if (!dev_priv->uncore.funcs.force_wake_get)
 		return;
 
 	WARN_ON(dev_priv->pm.suspended);
 
-	fw_domains &= dev_priv->uncore.fw_domains;
-
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
-
-	for_each_fw_domain_mask(domain, fw_domains, dev_priv, id) {
-		if (domain->wake_count++)
-			fw_domains &= ~(1 << id);
-	}
-
-	if (fw_domains)
-		dev_priv->uncore.funcs.force_wake_get(dev_priv, fw_domains);
-
+	__intel_uncore_forcewake_get(dev_priv, fw_domains);
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 }
 
 /**
- * intel_uncore_forcewake_put - release a forcewake domain reference
+ * intel_uncore_forcewake_get__locked - grab forcewake domain references
  * @dev_priv: i915 device instance
- * @fw_domains: forcewake domains to put references
+ * @fw_domains: forcewake domains to get reference on
  *
- * This function drops the device-level forcewakes for specified
- * domains obtained by intel_uncore_forcewake_get().
+ * See intel_uncore_forcewake_get(). This variant places the onus
+ * on the caller to explicitly handle the dev_priv->uncore.lock spinlock.
  */
-void intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
-				enum forcewake_domains fw_domains)
+void intel_uncore_forcewake_get__locked(struct drm_i915_private *dev_priv,
+					enum forcewake_domains fw_domains)
+{
+	assert_spin_locked(&dev_priv->uncore.lock);
+
+	if (!dev_priv->uncore.funcs.force_wake_get)
+		return;
+
+	__intel_uncore_forcewake_get(dev_priv, fw_domains);
+}
+
+static void __intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
+					 enum forcewake_domains fw_domains)
 {
-	unsigned long irqflags;
 	struct intel_uncore_forcewake_domain *domain;
 	enum forcewake_domain_id id;
 
@@ -435,8 +453,6 @@ void intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
 
 	fw_domains &= dev_priv->uncore.fw_domains;
 
-	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
-
 	for_each_fw_domain_mask(domain, fw_domains, dev_priv, id) {
 		if (WARN_ON(domain->wake_count == 0))
 			continue;
@@ -447,10 +463,48 @@ void intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
 		domain->wake_count++;
 		fw_domain_arm_timer(domain);
 	}
+}
 
+/**
+ * intel_uncore_forcewake_put - release a forcewake domain reference
+ * @dev_priv: i915 device instance
+ * @fw_domains: forcewake domains to put references
+ *
+ * This function drops the device-level forcewakes for specified
+ * domains obtained by intel_uncore_forcewake_get().
+ */
+void intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
+				enum forcewake_domains fw_domains)
+{
+	unsigned long irqflags;
+
+	if (!dev_priv->uncore.funcs.force_wake_put)
+		return;
+
+	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
+	__intel_uncore_forcewake_put(dev_priv, fw_domains);
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 }
 
+/**
+ * intel_uncore_forcewake_put__locked - grab forcewake domain references
+ * @dev_priv: i915 device instance
+ * @fw_domains: forcewake domains to get reference on
+ *
+ * See intel_uncore_forcewake_put(). This variant places the onus
+ * on the caller to explicitly handle the dev_priv->uncore.lock spinlock.
+ */
+void intel_uncore_forcewake_put__locked(struct drm_i915_private *dev_priv,
+					enum forcewake_domains fw_domains)
+{
+	assert_spin_locked(&dev_priv->uncore.lock);
+
+	if (!dev_priv->uncore.funcs.force_wake_put)
+		return;
+
+	__intel_uncore_forcewake_put(dev_priv, fw_domains);
+}
+
 void assert_forcewakes_inactive(struct drm_i915_private *dev_priv)
 {
 	struct intel_uncore_forcewake_domain *domain;