[PATCH 1/4] drm/i915: WARN in case PIPECONF is already enabled

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

After the modeset rework this really shouldn't be happening, so
transform it into a WARN. A stuck pipe is a bad signal and is one of
the things that can lead to full machine hangs.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8fd13ab..5f1399d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1737,7 +1737,7 @@ static void intel_enable_pipe(struct drm_i915_private *dev_priv, enum pipe pipe,
 
 	reg = PIPECONF(cpu_transcoder);
 	val = I915_READ(reg);
-	if (val & PIPECONF_ENABLE)
+	if (WARN_ON(val & PIPECONF_ENABLE))
 		return;
 
 	I915_WRITE(reg, val | PIPECONF_ENABLE);
-- 
1.8.3.1