diff mbox

[6/9] drm/i915: add the FBC mutex

Message ID 1419338145-1912-7-git-send-email-przanoni@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Paulo Zanoni Dec. 23, 2014, 12:35 p.m. UTC 
From: Paulo Zanoni <paulo.r.zanoni@intel.com>

Make sure we're not gonna have weird races in really weird cases where
a lot of different CRTCs are doing rendering and modesets at the same
time.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h  |  1 +
 drivers/gpu/drm/i915/intel_fbc.c | 80 +++++++++++++++++++++++++++++++---------
 2 files changed, 64 insertions(+), 17 deletions(-)

Comments

Chris Wilson Dec. 25, 2014, 10:25 a.m. UTC | #1 
On Tue, Dec 23, 2014 at 10:35:42AM -0200, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> 
> Make sure we're not gonna have weird races in really weird cases where
> a lot of different CRTCs are doing rendering and modesets at the same
> time.

You are not actually reducing the partial coverage from other locks,
particularly struct_mutex, so this doesn't look like the full improvement
it should be.
-Chris
Paulo Zanoni Dec. 26, 2014, 1:46 p.m. UTC | #2 
2014-12-25 8:25 GMT-02:00 Chris Wilson <chris@chris-wilson.co.uk>:
> On Tue, Dec 23, 2014 at 10:35:42AM -0200, Paulo Zanoni wrote:
>> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
>>
>> Make sure we're not gonna have weird races in really weird cases where
>> a lot of different CRTCs are doing rendering and modesets at the same
>> time.
>
> You are not actually reducing the partial coverage from other locks,
> particularly struct_mutex, so this doesn't look like the full improvement
> it should be.

Good point. I'll take a look at that.

> -Chris
>
> --
> Chris Wilson, Intel Open Source Technology Centre
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index f0419c8..18fcce4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -734,6 +734,7 @@  enum fb_op_origin {
 };
 
 struct i915_fbc {
+	struct mutex lock;
 	unsigned threshold;
 	unsigned int fb_id;
 	unsigned int possible_framebuffer_bits;
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index c6e688c..6611266 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -335,6 +335,7 @@  static void intel_fbc_work_fn(struct work_struct *__work)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	mutex_lock(&dev->struct_mutex);
+	mutex_lock(&dev_priv->fbc.lock);
 	if (work == dev_priv->fbc.fbc_work) {
 		/* Double check that we haven't switched fb without cancelling
 		 * the prior work.
@@ -349,6 +350,7 @@  static void intel_fbc_work_fn(struct work_struct *__work)
 
 		dev_priv->fbc.fbc_work = NULL;
 	}
+	mutex_unlock(&dev_priv->fbc.lock);
 	mutex_unlock(&dev->struct_mutex);
 
 	kfree(work);
@@ -356,6 +358,8 @@  static void intel_fbc_work_fn(struct work_struct *__work)
 
 static void intel_fbc_cancel_work(struct drm_i915_private *dev_priv)
 {
+	lockdep_assert_held(&dev_priv->fbc.lock);
+
 	if (dev_priv->fbc.fbc_work == NULL)
 		return;
 
@@ -383,6 +387,8 @@  static void intel_fbc_enable(struct drm_crtc *crtc)
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	lockdep_assert_held(&dev_priv->fbc.lock);
+
 	if (!dev_priv->display.enable_fbc)
 		return;
 
@@ -417,16 +423,12 @@  static void intel_fbc_enable(struct drm_crtc *crtc)
 	schedule_delayed_work(&work->work, msecs_to_jiffies(50));
 }
 
-/**
- * intel_fbc_disable - disable FBC
- * @dev: the drm_device
- *
- * This function disables FBC.
- */
-void intel_fbc_disable(struct drm_device *dev)
+static void __intel_fbc_disable(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	lockdep_assert_held(&dev_priv->fbc.lock);
+
 	intel_fbc_cancel_work(dev_priv);
 
 	if (!dev_priv->display.disable_fbc)
@@ -436,6 +438,21 @@  void intel_fbc_disable(struct drm_device *dev)
 	dev_priv->fbc.crtc = NULL;
 }
 
+/**
+ * intel_fbc_disable - disable FBC
+ * @dev: the drm_device
+ *
+ * This function disables FBC.
+ */
+void intel_fbc_disable(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	mutex_lock(&dev_priv->fbc.lock);
+	__intel_fbc_disable(dev);
+	mutex_unlock(&dev_priv->fbc.lock);
+}
+
 static bool set_no_fbc_reason(struct drm_i915_private *dev_priv,
 			      enum no_fbc_reason reason)
 {
@@ -484,7 +501,7 @@  static struct drm_crtc *intel_fbc_find_crtc(struct drm_i915_private *dev_priv)
 }
 
 /**
- * intel_fbc_update - enable/disable FBC as needed
+ * __intel_fbc_update - enable/disable FBC as needed, unlocked
  * @dev: the drm_device
  *
  * Set up the framebuffer compression hardware at mode set time.  We
@@ -502,7 +519,7 @@  static struct drm_crtc *intel_fbc_find_crtc(struct drm_i915_private *dev_priv)
  *
  * We need to enable/disable FBC on a global basis.
  */
-void intel_fbc_update(struct drm_device *dev)
+static void __intel_fbc_update(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_crtc *crtc = NULL;
@@ -512,6 +529,8 @@  void intel_fbc_update(struct drm_device *dev)
 	const struct drm_display_mode *adjusted_mode;
 	unsigned int max_width, max_height;
 
+	lockdep_assert_held(&dev_priv->fbc.lock);
+
 	if (!HAS_FBC(dev))
 		return;
 
@@ -631,7 +650,7 @@  void intel_fbc_update(struct drm_device *dev)
 		 * some point. And we wait before enabling FBC anyway.
 		 */
 		DRM_DEBUG_KMS("disabling active FBC for update\n");
-		intel_fbc_disable(dev);
+		__intel_fbc_disable(dev);
 	}
 
 	if (i915_gem_stolen_setup_compression(dev, obj->base.size,
@@ -649,11 +668,26 @@  out_disable:
 	/* Multiple disables should be harmless */
 	if (intel_fbc_enabled(dev)) {
 		DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
-		intel_fbc_disable(dev);
+		__intel_fbc_disable(dev);
 	}
 	i915_gem_stolen_cleanup_compression(dev);
 }
 
+/*
+ * intel_fbc_update - enable/disable FBC as needed
+ * @dev: the drm_device
+ *
+ * This function reevaluates the overall state and enables or disables FBC.
+ */
+void intel_fbc_update(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	mutex_lock(&dev_priv->fbc.lock);
+	__intel_fbc_update(dev);
+	mutex_unlock(&dev_priv->fbc.lock);
+}
+
 void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
 			  unsigned int frontbuffer_bits,
 			  enum fb_op_origin origin)
@@ -661,8 +695,10 @@  void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
 	struct drm_device *dev = dev_priv->dev;
 	unsigned int fbc_bits;
 
+	mutex_lock(&dev_priv->fbc.lock);
+
 	if (origin == ORIGIN_GTT)
-		return;
+		goto out;
 
 	if (dev_priv->fbc.enabled)
 		fbc_bits = INTEL_FRONTBUFFER_PRIMARY(dev_priv->fbc.crtc->pipe);
@@ -673,9 +709,12 @@  void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
 		fbc_bits = dev_priv->fbc.possible_framebuffer_bits;
 
 	if ((fbc_bits & frontbuffer_bits) == 0)
-		return;
+		goto out;
 
-	intel_fbc_disable(dev);
+	__intel_fbc_disable(dev);
+
+out:
+	mutex_unlock(&dev_priv->fbc.lock);
 }
 
 void intel_fbc_flush(struct drm_i915_private *dev_priv,
@@ -686,6 +725,8 @@  void intel_fbc_flush(struct drm_i915_private *dev_priv,
 	unsigned int fbc_bits = 0;
 	bool fbc_enabled;
 
+	mutex_lock(&dev_priv->fbc.lock);
+
 	if (dev_priv->fbc.enabled)
 		fbc_bits = INTEL_FRONTBUFFER_PRIMARY(dev_priv->fbc.crtc->pipe);
 	else
@@ -693,7 +734,7 @@  void intel_fbc_flush(struct drm_i915_private *dev_priv,
 
 	/* These are not the planes you are looking for. */
 	if ((frontbuffer_bits & fbc_bits) == 0)
-		return;
+		goto out;
 
 	fbc_enabled = intel_fbc_enabled(dev);
 
@@ -703,12 +744,15 @@  void intel_fbc_flush(struct drm_i915_private *dev_priv,
 			if (origin == ORIGIN_CS || origin == ORIGIN_CPU)
 				intel_fbc_nuke(dev_priv);
 		} else {
-			intel_fbc_update(dev);
+			__intel_fbc_update(dev);
 		}
 	} else {
 		if (fbc_enabled)
-			intel_fbc_disable(dev);
+			__intel_fbc_disable(dev);
 	}
+
+out:
+	mutex_unlock(&dev_priv->fbc.lock);
 }
 
 /**
@@ -721,6 +765,8 @@  void intel_fbc_init(struct drm_i915_private *dev_priv)
 {
 	enum pipe pipe;
 
+	mutex_init(&dev_priv->fbc.lock);
+
 	if (!HAS_FBC(dev_priv)) {
 		dev_priv->fbc.enabled = false;
 		dev_priv->fbc.no_fbc_reason = FBC_UNSUPPORTED;