[PATCH 4/5] drm/i915: Simplify the uncleared FIFO underrun detection

[ville.syrjala@linux.intel.com]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Checking whether the error interrupt was enabled or not isn't really
necessary when we check for uncleared FIFO underruns. If it was enabled
we'll race with the interrupt handler a bit, but that seems OK as we
still claim the interrupt.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 862964f..dd6e359 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -337,13 +337,9 @@ static void ivybridge_set_fifo_underrun_reporting(struct drm_device *dev,
 
 		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))) {
+		if (I915_READ(GEN7_ERR_INT) & ERR_INT_FIFO_UNDERRUN(pipe)) {
 			DRM_ERROR("uncleared fifo underrun on pipe %c\n",
 				  pipe_name(pipe));
 		}
@@ -421,14 +417,9 @@ static void cpt_set_fifo_underrun_reporting(struct drm_device *dev,
 
 		ibx_enable_display_interrupt(dev_priv, SDE_ERROR_CPT);
 	} else {
-		uint32_t tmp = I915_READ(SERR_INT);
-		bool was_enabled = !(I915_READ(SDEIMR) & SDE_ERROR_CPT);
-
-		/* Change the state _after_ we've read out the current one. */
 		ibx_disable_display_interrupt(dev_priv, SDE_ERROR_CPT);
 
-		if (!was_enabled &&
-		    (tmp & SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder))) {
+		if (I915_READ(SERR_INT) & SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) {
 			DRM_ERROR("uncleared pch fifo underrun on pch transcoder %c\n",
 				  transcoder_name(pch_transcoder));
 		}
-- 
1.8.5.5

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