1 files changed, 13 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index dd9d9997e90b..76e977b0070e 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -154,21 +154,27 @@ static void ironlake_set_fifo_underrun_reporting(struct drm_device *dev,
 }
 
 static void ivybridge_set_fifo_underrun_reporting(struct drm_device *dev,
-                                                  bool enable)
+                                                  enum pipe pipe, bool enable)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
-
         if (enable) {
+                I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));
+
                 if (!ivb_can_enable_err_int(dev))
                         return;
 
-                I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN_A |
-                                         ERR_INT_FIFO_UNDERRUN_B |
-                                         ERR_INT_FIFO_UNDERRUN_C);
-
                 ironlake_enable_display_irq(dev_priv, DE_ERR_INT_IVB);
         } else {
+                bool was_enabled = !(I915_READ(DEIMR) & DE_ERR_INT_IVB);
+
+                /* Change the state _after_ we've read out the current one. */
                 ironlake_disable_display_irq(dev_priv, DE_ERR_INT_IVB);
+
+                if (!was_enabled &&
+                    (I915_READ(GEN7_ERR_INT) & ERR_INT_FIFO_UNDERRUN(pipe))) {
+                        DRM_DEBUG_KMS("uncleared fifo underrun on pipe %c\n",
+                                      pipe_name(pipe));
+                }
         }
 }
 
@@ -274,7 +280,7 @@ bool intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
         if (IS_GEN5(dev) || IS_GEN6(dev))
                 ironlake_set_fifo_underrun_reporting(dev, pipe, enable);
         else if (IS_GEN7(dev))
-                ivybridge_set_fifo_underrun_reporting(dev, enable);
+                ivybridge_set_fifo_underrun_reporting(dev, pipe, enable);
 
 done:
         spin_unlock_irqrestore(&dev_priv->irq_lock, flags);