drm/i915: vlv: handle only enabled pipestat interrupt events

Atm we call the handlers for pending pipestat interrupt events even if
they aren't explicitly enabled by i915_enable_pipestat(). This isn't an
issue for events other than the vblank start event, since those are
always enabled anyways. Otoh, we enable the vblank start event
on-demand, so we'll end up calling the vblank handler at times when they
are disabled.

I haven't checked if this causes any real problem, but for consistency
and to remove some overhead we should still fix this by clearing /
handling only the enabled interrupt events. Also this is a dependency
for the upcoming VLV power domain patchset where we need to disable all
the pipestat interrupts whenever the display power well is off.

v2:
- inline the status->enable mask mapping (Ville)
- don't check for invalid PSR bit on platforms other than VLV (Ville)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Frob conflict due to different merge order.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1436,6 +1436,7 @@ typedef struct drm_i915_private {
 	};
 	u32 gt_irq_mask;
 	u32 pm_irq_mask;
+	u32 pipestat_irq_mask[I915_MAX_PIPES];
 
 	struct work_struct hotplug_work;
 	bool enable_hotplug_processing;

drivers/gpu/drm/i915/i915_irq.c

@@ -419,6 +419,16 @@ bool intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
 	return ret;
 }
 
+static bool __cpu_fifo_underrun_reporting_enabled(struct drm_device *dev,
+						  enum pipe pipe)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+
+	return !intel_crtc->cpu_fifo_underrun_disabled;
+}
+
 /**
  * intel_set_pch_fifo_underrun_reporting - enable/disable FIFO underrun messages
  * @dev: drm device
@@ -488,6 +498,8 @@ __i915_enable_pipestat(struct drm_i915_private *dev_priv, enum pipe pipe,
 	if ((pipestat & enable_mask) == enable_mask)
 		return;
 
+	dev_priv->pipestat_irq_mask[pipe] |= status_mask;
+
 	/* Enable the interrupt, clear any pending status */
 	pipestat |= enable_mask | status_mask;
 	I915_WRITE(reg, pipestat);
@@ -510,6 +522,8 @@ __i915_disable_pipestat(struct drm_i915_private *dev_priv, enum pipe pipe,
 	if ((pipestat & enable_mask) == 0)
 		return;
 
+	dev_priv->pipestat_irq_mask[pipe] &= ~status_mask;
+
 	pipestat &= ~enable_mask;
 	I915_WRITE(reg, pipestat);
 	POSTING_READ(reg);
@@ -1540,18 +1554,33 @@ static void gen6_rps_irq_handler(struct drm_i915_private *dev_priv, u32 pm_iir)
 static void valleyview_pipestat_irq_handler(struct drm_device *dev, u32 iir)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 pipe_stats[I915_MAX_PIPES];
+	u32 pipe_stats[I915_MAX_PIPES] = { };
 	int pipe;
 
 	spin_lock(&dev_priv->irq_lock);
 	for_each_pipe(pipe) {
-		int reg = PIPESTAT(pipe);
+		int reg;
+		u32 mask;
+
+		if (!dev_priv->pipestat_irq_mask[pipe] &&
+		    !__cpu_fifo_underrun_reporting_enabled(dev, pipe))
+			continue;
+
+		reg = PIPESTAT(pipe);
 		pipe_stats[pipe] = I915_READ(reg);
 
 		/*
 		 * Clear the PIPE*STAT regs before the IIR
 		 */
-		if (pipe_stats[pipe] & 0x8000ffff)
+		mask = PIPESTAT_INT_ENABLE_MASK;
+		if (__cpu_fifo_underrun_reporting_enabled(dev, pipe))
+			mask |= PIPE_FIFO_UNDERRUN_STATUS;
+		if (iir & I915_DISPLAY_PIPE_EVENT_INTERRUPT(pipe))
+			mask |= dev_priv->pipestat_irq_mask[pipe];
+		pipe_stats[pipe] &= mask;
+
+		if (pipe_stats[pipe] & (PIPE_FIFO_UNDERRUN_STATUS |
+					PIPESTAT_INT_STATUS_MASK))
 			I915_WRITE(reg, pipe_stats[pipe]);
 	}
 	spin_unlock(&dev_priv->irq_lock);

drivers/gpu/drm/i915/i915_reg.h

@@ -997,6 +997,10 @@
 #define I915_DISPLAY_PIPE_A_EVENT_INTERRUPT		(1<<6)
 #define I915_DISPLAY_PIPE_B_VBLANK_INTERRUPT		(1<<5)
 #define I915_DISPLAY_PIPE_B_EVENT_INTERRUPT		(1<<4)
+#define I915_DISPLAY_PIPE_EVENT_INTERRUPT(pipe)				\
+	((pipe) == PIPE_A ? I915_DISPLAY_PIPE_A_EVENT_INTERRUPT :	\
+	 I915_DISPLAY_PIPE_B_EVENT_INTERRUPT)
+
 #define I915_DEBUG_INTERRUPT				(1<<2)
 #define I915_USER_INTERRUPT				(1<<1)
 #define I915_ASLE_INTERRUPT				(1<<0)