[Intel-gfx] [PATCH 13/24] drm/i915: kill lpt pch transcoder->crtc mapping code for fifo underruns

[Daniel Vetter]

It's racy: There's no guarantee that we won't walk this code (due to a
pch fifo underrun interrupt) while someone is changing the pointers
around.

The only reason we do this is to use the righ crtc for the pch fifo
underrun accounting. But we never expose this to userspace, so
essentially no one really cares if we use the "wrong" crtc.

So let's just rip it out.

With this patch fifo underrun code will always use crtc A for tracking
underruns on the (only) pch transcoder on LPT.

Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_irq.c | 33 +++++++--------------------------
 1 file changed, 7 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index bb26555..b98ea4e 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -193,13 +193,13 @@ static void ibx_display_interrupt_update(struct drm_i915_private *dev_priv,
 	POSTING_READ(SDEIMR);
 }
 
-static void ibx_set_fifo_underrun_reporting(struct intel_crtc *crtc,
+static void ibx_set_fifo_underrun_reporting(struct drm_device *dev,
+					    enum transcoder pch_transcoder,
 					    bool enable)
 {
-	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	uint32_t bit = (crtc->pipe == PIPE_A) ? SDE_TRANSA_FIFO_UNDER :
-						SDE_TRANSB_FIFO_UNDER;
+	uint32_t bit = (pch_transcoder == TRANSCODER_A) ?
+		       SDE_TRANSA_FIFO_UNDER : SDE_TRANSB_FIFO_UNDER;
 
 	ibx_display_interrupt_update(dev_priv, bit,
 				     enable ? bit : 0);
@@ -292,30 +292,11 @@ bool intel_set_pch_fifo_underrun_reporting(struct drm_device *dev,
 					   bool enable)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	enum pipe p;
-	struct drm_crtc *crtc;
-	struct intel_crtc *intel_crtc;
+	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pch_transcoder];
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	unsigned long flags;
 	bool ret;
 
-	if (HAS_PCH_LPT(dev)) {
-		crtc = NULL;
-		for_each_pipe(p) {
-			struct drm_crtc *c = dev_priv->pipe_to_crtc_mapping[p];
-			if (intel_pipe_has_type(c, INTEL_OUTPUT_ANALOG)) {
-				crtc = c;
-				break;
-			}
-		}
-		if (!crtc) {
-			DRM_ERROR("PCH FIFO underrun, but no CRTC using the PCH found\n");
-			return false;
-		}
-	} else {
-		crtc = dev_priv->pipe_to_crtc_mapping[pch_transcoder];
-	}
-	intel_crtc = to_intel_crtc(crtc);
-
 	spin_lock_irqsave(&dev_priv->irq_lock, flags);
 
 	ret = !intel_crtc->pch_fifo_underrun_disabled;
@@ -326,7 +307,7 @@ bool intel_set_pch_fifo_underrun_reporting(struct drm_device *dev,
 	intel_crtc->pch_fifo_underrun_disabled = !enable;
 
 	if (HAS_PCH_IBX(dev))
-		ibx_set_fifo_underrun_reporting(intel_crtc, enable);
+		ibx_set_fifo_underrun_reporting(dev, pch_transcoder, enable);
 	else
 		cpt_set_fifo_underrun_reporting(dev, pch_transcoder, enable);
 
-- 
1.8.1.4