[Intel-gfx] [PATCH 61/70] drm/i915: Make fb_tracking.lock a spinlock

[Chris Wilson]

We only need a very lightweight mechanism here as the locking is only
used for co-ordinating a bitfield.

Also double check that the object is still pinned to the display plane
before processing the state change.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h          |  2 +-
 drivers/gpu/drm/i915/i915_gem.c          |  2 +-
 drivers/gpu/drm/i915/intel_frontbuffer.c | 40 +++++++++++++++++---------------
 3 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 97372869097f..eeffefa10612 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1545,7 +1545,7 @@ struct intel_pipe_crc {
 };
 
 struct i915_frontbuffer_tracking {
-	struct mutex lock;
+	spinlock_t lock;
 
 	/*
 	 * Tracking bits for delayed frontbuffer flushing du to gpu activity or
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e9f2d2b102de..43baac2c1e20 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5260,7 +5260,7 @@ i915_gem_load(struct drm_device *dev)
 
 	i915_gem_shrinker_init(dev_priv);
 
-	mutex_init(&dev_priv->fb_tracking.lock);
+	spin_lock_init(&dev_priv->fb_tracking.lock);
 }
 
 void i915_gem_release(struct drm_device *dev, struct drm_file *file)
diff --git a/drivers/gpu/drm/i915/intel_frontbuffer.c b/drivers/gpu/drm/i915/intel_frontbuffer.c
index a20cffb78c0f..28ce2ab94189 100644
--- a/drivers/gpu/drm/i915/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/intel_frontbuffer.c
@@ -139,16 +139,14 @@ void intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
-	if (!obj->frontbuffer_bits)
+	if (!obj->frontbuffer_bits || !obj->pin_display)
 		return;
 
 	if (ring) {
-		mutex_lock(&dev_priv->fb_tracking.lock);
-		dev_priv->fb_tracking.busy_bits
-			|= obj->frontbuffer_bits;
-		dev_priv->fb_tracking.flip_bits
-			&= ~obj->frontbuffer_bits;
-		mutex_unlock(&dev_priv->fb_tracking.lock);
+		spin_lock(&dev_priv->fb_tracking.lock);
+		dev_priv->fb_tracking.busy_bits |= obj->frontbuffer_bits;
+		dev_priv->fb_tracking.flip_bits &= ~obj->frontbuffer_bits;
+		spin_unlock(&dev_priv->fb_tracking.lock);
 	}
 
 	intel_mark_fb_busy(dev, obj->frontbuffer_bits, ring);
@@ -175,9 +173,12 @@ void intel_frontbuffer_flush(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	/* Delay flushing when rings are still busy.*/
-	mutex_lock(&dev_priv->fb_tracking.lock);
+	spin_lock(&dev_priv->fb_tracking.lock);
 	frontbuffer_bits &= ~dev_priv->fb_tracking.busy_bits;
-	mutex_unlock(&dev_priv->fb_tracking.lock);
+	spin_unlock(&dev_priv->fb_tracking.lock);
+
+	if (frontbuffer_bits == 0)
+		return;
 
 	intel_mark_fb_busy(dev, frontbuffer_bits, NULL);
 
@@ -204,21 +205,21 @@ void intel_fb_obj_flush(struct drm_i915_gem_object *obj,
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
-	if (!obj->frontbuffer_bits)
+	if (!obj->frontbuffer_bits || !obj->pin_display)
 		return;
 
 	frontbuffer_bits = obj->frontbuffer_bits;
 
 	if (retire) {
-		mutex_lock(&dev_priv->fb_tracking.lock);
+		spin_lock(&dev_priv->fb_tracking.lock);
 		/* Filter out new bits since rendering started. */
 		frontbuffer_bits &= dev_priv->fb_tracking.busy_bits;
-
 		dev_priv->fb_tracking.busy_bits &= ~frontbuffer_bits;
-		mutex_unlock(&dev_priv->fb_tracking.lock);
+		spin_unlock(&dev_priv->fb_tracking.lock);
 	}
 
-	intel_frontbuffer_flush(dev, frontbuffer_bits);
+	if (frontbuffer_bits)
+		intel_frontbuffer_flush(dev, frontbuffer_bits);
 }
 
 /**
@@ -238,11 +239,11 @@ void intel_frontbuffer_flip_prepare(struct drm_device *dev,
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	mutex_lock(&dev_priv->fb_tracking.lock);
+	spin_lock(&dev_priv->fb_tracking.lock);
 	dev_priv->fb_tracking.flip_bits |= frontbuffer_bits;
 	/* Remove stale busy bits due to the old buffer. */
 	dev_priv->fb_tracking.busy_bits &= ~frontbuffer_bits;
-	mutex_unlock(&dev_priv->fb_tracking.lock);
+	spin_unlock(&dev_priv->fb_tracking.lock);
 }
 
 /**
@@ -260,11 +261,12 @@ void intel_frontbuffer_flip_complete(struct drm_device *dev,
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	mutex_lock(&dev_priv->fb_tracking.lock);
+	spin_lock(&dev_priv->fb_tracking.lock);
 	/* Mask any cancelled flips. */
 	frontbuffer_bits &= dev_priv->fb_tracking.flip_bits;
 	dev_priv->fb_tracking.flip_bits &= ~frontbuffer_bits;
-	mutex_unlock(&dev_priv->fb_tracking.lock);
+	spin_unlock(&dev_priv->fb_tracking.lock);
 
-	intel_frontbuffer_flush(dev, frontbuffer_bits);
+	if (frontbuffer_bits)
+		intel_frontbuffer_flush(dev, frontbuffer_bits);
 }
-- 
2.1.4