[PATCH v2 2/2] drm/i915: Ignore transcoder B/C on LPT/WPT FIFO underrun handling

[ville.syrjala@linux.intel.com]

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

LPT/WPT only have transcoder A, so we shouldn't look at FIFO underruns
for transocoder B/C. And more importnatnly we should not consider
the state of underrun reporting for transcoders B/C when checking
whether we can enable the south error interrupt.

The whole thing is a bit of mess since we store the underrun reporting
state for transcoder A under intel_crtc for pipe A, irrespective of
which pipe may actually be driving the transcoder. But I figured trying
to change that would result in more churn.

Caveat: Still untested

v2: Use HAS_PCH_LPT_H instead of HAS_DDI
    Use cpt_check_pch_fifo_underruns() on LPT-H/WPT-H too

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_fifo_underrun.c | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_fifo_underrun.c b/drivers/gpu/drm/i915/intel_fifo_underrun.c
index bda526660e20..3d3acc8b8367 100644
--- a/drivers/gpu/drm/i915/intel_fifo_underrun.c
+++ b/drivers/gpu/drm/i915/intel_fifo_underrun.c
@@ -48,6 +48,14 @@
  * The code also supports underrun detection on the PCH transcoder.
  */
 
+static bool cpt_transcoder_exists(struct drm_i915_private *dev_priv,
+				  enum transcoder pch_transcoder)
+{
+	/* LPT-H/WPT-H have only transcoder A */
+	return HAS_PCH_CPT(dev_priv) ||
+		(HAS_PCH_LPT_H(dev_priv) && pch_transcoder == TRANSCODER_A);
+}
+
 static bool ivb_can_enable_err_int(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -69,13 +77,16 @@ static bool ivb_can_enable_err_int(struct drm_device *dev)
 static bool cpt_can_enable_serr_int(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	enum pipe pipe;
-	struct intel_crtc *crtc;
+	enum transcoder pch_transcoder;
 
 	assert_spin_locked(&dev_priv->irq_lock);
 
-	for_each_pipe(dev_priv, pipe) {
-		crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
+	for_each_pipe(dev_priv, pch_transcoder) {
+		struct intel_crtc *crtc =
+			to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pch_transcoder]);
+
+		if (!cpt_transcoder_exists(dev_priv, pch_transcoder))
+			continue;
 
 		if (crtc->pch_fifo_underrun_disabled)
 			return false;
@@ -206,6 +217,9 @@ static void cpt_check_pch_fifo_underruns(struct intel_crtc *crtc)
 
 	assert_spin_locked(&dev_priv->irq_lock);
 
+	if (!cpt_transcoder_exists(dev_priv, pch_transcoder))
+		return;
+
 	if ((serr_int & SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) == 0)
 		return;
 
@@ -222,6 +236,9 @@ static void cpt_set_fifo_underrun_reporting(struct drm_device *dev,
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	if (!cpt_transcoder_exists(dev_priv, pch_transcoder))
+		return;
+
 	if (enable) {
 		I915_WRITE(SERR_INT,
 			   SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));
@@ -436,7 +453,7 @@ void intel_check_pch_fifo_underruns(struct drm_i915_private *dev_priv)
 		if (crtc->pch_fifo_underrun_disabled)
 			continue;
 
-		if (HAS_PCH_CPT(dev_priv))
+		if (HAS_PCH_CPT(dev_priv) || HAS_PCH_LPT_H(dev_priv))
 			cpt_check_pch_fifo_underruns(crtc);
 	}
 
-- 
2.4.10

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