drm/i915: Move the irq wait queue initialisation into the ring init

Required so that we don't obliterate the queue if initialising the
rings after the global IRQ handler is installed.

[Jesse, you recently looked at refactoring the IRQ installation
routines, does moving the initialisation of ring buffer data structures away
from that routine make sense in your grand scheme?]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -1688,12 +1688,6 @@ int i915_driver_irq_postinstall(struct drm_device *dev)
 	u32 enable_mask = I915_INTERRUPT_ENABLE_FIX | I915_INTERRUPT_ENABLE_VAR;
 	u32 error_mask;
 
-	DRM_INIT_WAITQUEUE(&dev_priv->ring[RCS].irq_queue);
-	if (HAS_BSD(dev))
-		DRM_INIT_WAITQUEUE(&dev_priv->ring[VCS].irq_queue);
-	if (HAS_BLT(dev))
-		DRM_INIT_WAITQUEUE(&dev_priv->ring[BCS].irq_queue);
-
 	dev_priv->vblank_pipe = DRM_I915_VBLANK_PIPE_A | DRM_I915_VBLANK_PIPE_B;
 
 	if (HAS_PCH_SPLIT(dev))

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -800,6 +800,7 @@ int intel_init_ring_buffer(struct drm_device *dev,
 	INIT_LIST_HEAD(&ring->request_list);
 	INIT_LIST_HEAD(&ring->gpu_write_list);
 
+	init_waitqueue_head(&ring->irq_queue);
 	spin_lock_init(&ring->irq_lock);
 	ring->irq_mask = ~0;