[Intel-gfx] [PATCH] drm/i915: Don't enable display error interrupts from the start

[Daniel Vetter]

We need to enable interrupt processing before all the modeset
state is set up. But that means we can fall over when we get a pipe
underrun. This shouldn't happen as long as the bios works correctly
but as usual this turns out to be wishful thinking.

So disable error interrupts at irq install time and rely on the
re-enabling code in the modeset functions to take care of this.

Note that due to the SDE interrupt handling race we must
uncondtionally enable all interrupt sources in SDEIER, hence no need
to enable the SERR bit specifically.

On gmch platforms we don't have an explicit enable/mask bit for fifo
underruns. Fixing this up would require a bit of software tracking,
hence is material for a separate patch. To make this possible we need
to switch all gmch platforms to the new pipestat interrupt handling
scheme Ville implemented for vlv, and then also add a safe form of sw
state checking to __cpu_fifo_underrun_reporting_enabled a bit.

v2: Also handle the ilk/snb cpu fifo underrun bits accordingly.
Spotted by Ville.

Reported-by: Rob Clark <robdclark at gmail.com>
Cc: Rob Clark <robdclark at gmail.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: stable at vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_irq.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index bd1f90645697..18b9f600fe25 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2922,7 +2922,7 @@ static void ibx_irq_postinstall(struct drm_device *dev)
 		mask = SDE_GMBUS | SDE_AUX_MASK | SDE_TRANSB_FIFO_UNDER |
 		       SDE_TRANSA_FIFO_UNDER | SDE_POISON;
 	} else {
-		mask = SDE_GMBUS_CPT | SDE_AUX_MASK_CPT | SDE_ERROR_CPT;
+		mask = SDE_GMBUS_CPT | SDE_AUX_MASK_CPT;
 
 		I915_WRITE(SERR_INT, I915_READ(SERR_INT));
 	}
@@ -2982,20 +2982,19 @@ static int ironlake_irq_postinstall(struct drm_device *dev)
 		display_mask = (DE_MASTER_IRQ_CONTROL | DE_GSE_IVB |
 				DE_PCH_EVENT_IVB | DE_PLANEC_FLIP_DONE_IVB |
 				DE_PLANEB_FLIP_DONE_IVB |
-				DE_PLANEA_FLIP_DONE_IVB | DE_AUX_CHANNEL_A_IVB |
-				DE_ERR_INT_IVB);
+				DE_PLANEA_FLIP_DONE_IVB | DE_AUX_CHANNEL_A_IVB);
 		extra_mask = (DE_PIPEC_VBLANK_IVB | DE_PIPEB_VBLANK_IVB |
-			      DE_PIPEA_VBLANK_IVB);
+			      DE_PIPEA_VBLANK_IVB | DE_ERR_INT_IVB);
 
 		I915_WRITE(GEN7_ERR_INT, I915_READ(GEN7_ERR_INT));
 	} else {
 		display_mask = (DE_MASTER_IRQ_CONTROL | DE_GSE | DE_PCH_EVENT |
 				DE_PLANEA_FLIP_DONE | DE_PLANEB_FLIP_DONE |
 				DE_AUX_CHANNEL_A |
-				DE_PIPEB_FIFO_UNDERRUN | DE_PIPEA_FIFO_UNDERRUN |
 				DE_PIPEB_CRC_DONE | DE_PIPEA_CRC_DONE |
 				DE_POISON);
-		extra_mask = DE_PIPEA_VBLANK | DE_PIPEB_VBLANK | DE_PCU_EVENT;
+		extra_mask = DE_PIPEA_VBLANK | DE_PIPEB_VBLANK | DE_PCU_EVENT |
+				DE_PIPEB_FIFO_UNDERRUN | DE_PIPEA_FIFO_UNDERRUN;
 	}
 
 	dev_priv->irq_mask = ~display_mask;
@@ -3111,9 +3110,9 @@ static void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 	uint32_t de_pipe_masked = GEN8_PIPE_FLIP_DONE |
 		GEN8_PIPE_CDCLK_CRC_DONE |
-		GEN8_PIPE_FIFO_UNDERRUN |
 		GEN8_DE_PIPE_IRQ_FAULT_ERRORS;
-	uint32_t de_pipe_enables = de_pipe_masked | GEN8_PIPE_VBLANK;
+	uint32_t de_pipe_enables = de_pipe_masked | GEN8_PIPE_VBLANK |
+		GEN8_PIPE_FIFO_UNDERRUN;
 	int pipe;
 	dev_priv->de_irq_mask[PIPE_A] = ~de_pipe_masked;
 	dev_priv->de_irq_mask[PIPE_B] = ~de_pipe_masked;
-- 
1.8.5.2