[PATCH] drm/i915: make locking requirement for pipestat changes more explicit

[Jani Nikula <jani.nikula@intel.com>]

Warn on missing locking in pipestat enable/disable, and fix calls that
would trigger this.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

---

Daniel, is this more to your liking?

I don't have a machine handy to actually test this right now...
---
 drivers/gpu/drm/i915/i915_irq.c |   21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 03a31be..efedf61 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -325,6 +325,8 @@ i915_enable_pipestat(drm_i915_private_t *dev_priv, int pipe, u32 mask)
 	u32 reg = PIPESTAT(pipe);
 	u32 pipestat = I915_READ(reg) & 0x7fff0000;
 
+	WARN_ON(!spin_is_locked(&dev_priv->irq_lock));
+
 	if ((pipestat & mask) == mask)
 		return;
 
@@ -340,6 +342,8 @@ i915_disable_pipestat(drm_i915_private_t *dev_priv, int pipe, u32 mask)
 	u32 reg = PIPESTAT(pipe);
 	u32 pipestat = I915_READ(reg) & 0x7fff0000;
 
+	WARN_ON(!spin_is_locked(&dev_priv->irq_lock));
+
 	if ((pipestat & mask) == 0)
 		return;
 
@@ -354,18 +358,13 @@ i915_disable_pipestat(drm_i915_private_t *dev_priv, int pipe, u32 mask)
 static void i915_enable_asle_pipestat(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	unsigned long irqflags;
 
 	if (!dev_priv->opregion.asle || !IS_MOBILE(dev))
 		return;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
-
 	i915_enable_pipestat(dev_priv, 1, PIPE_LEGACY_BLC_EVENT_ENABLE);
 	if (INTEL_INFO(dev)->gen >= 4)
 		i915_enable_pipestat(dev_priv, 0, PIPE_LEGACY_BLC_EVENT_ENABLE);
-
-	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 }
 
 /**
@@ -2650,6 +2649,7 @@ static int valleyview_irq_postinstall(struct drm_device *dev)
 	u32 enable_mask;
 	u32 pipestat_enable = PLANE_FLIP_DONE_INT_EN_VLV;
 	u32 render_irqs;
+	unsigned long irqflags;
 
 	enable_mask = I915_DISPLAY_PORT_INTERRUPT;
 	enable_mask |= I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
@@ -2675,9 +2675,11 @@ static int valleyview_irq_postinstall(struct drm_device *dev)
 	I915_WRITE(PIPESTAT(1), 0xffff);
 	POSTING_READ(VLV_IER);
 
+	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
 	i915_enable_pipestat(dev_priv, 0, pipestat_enable);
 	i915_enable_pipestat(dev_priv, 0, PIPE_GMBUS_EVENT_ENABLE);
 	i915_enable_pipestat(dev_priv, 1, pipestat_enable);
+	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
 	I915_WRITE(VLV_IIR, 0xffffffff);
 	I915_WRITE(VLV_IIR, 0xffffffff);
@@ -2934,6 +2936,7 @@ static int i915_irq_postinstall(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	u32 enable_mask;
+	unsigned long irqflags;
 
 	I915_WRITE(EMR, ~(I915_ERROR_PAGE_TABLE | I915_ERROR_MEMORY_REFRESH));
 
@@ -2967,7 +2970,9 @@ static int i915_irq_postinstall(struct drm_device *dev)
 	I915_WRITE(IER, enable_mask);
 	POSTING_READ(IER);
 
+	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
 	i915_enable_asle_pipestat(dev);
+	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
 	return 0;
 }
@@ -3159,6 +3164,7 @@ static int i965_irq_postinstall(struct drm_device *dev)
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	u32 enable_mask;
 	u32 error_mask;
+	unsigned long irqflags;
 
 	/* Unmask the interrupts that we always want on. */
 	dev_priv->irq_mask = ~(I915_ASLE_INTERRUPT |
@@ -3177,7 +3183,10 @@ static int i965_irq_postinstall(struct drm_device *dev)
 	if (IS_G4X(dev))
 		enable_mask |= I915_BSD_USER_INTERRUPT;
 
+	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
 	i915_enable_pipestat(dev_priv, 0, PIPE_GMBUS_EVENT_ENABLE);
+	i915_enable_asle_pipestat(dev);
+	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
 	/*
 	 * Enable some error detection, note the instruction error mask
@@ -3201,8 +3210,6 @@ static int i965_irq_postinstall(struct drm_device *dev)
 	I915_WRITE(PORT_HOTPLUG_EN, 0);
 	POSTING_READ(PORT_HOTPLUG_EN);
 
-	i915_enable_asle_pipestat(dev);
-
 	return 0;
 }
 
-- 
1.7.10.4