drm/i915: Handle the no-interrupts case for UMS by polling

If the driver calls into the kernel to wait for a breadcrumb to pass,
but hasn't enabled interrupts, fallback to polling the breadcrumb value.

Reported-by: Chris Clayton <chris2553@googlemail.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 98106b7efa8b64dc4bee13db39ad09103290dfe3..4b5a35c88bec45b600a63ceb3537a211c89e3410 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1293,12 +1293,12 @@ static int i915_wait_irq(struct drm_device * dev, int irq_nr)
        if (master_priv->sarea_priv)
                master_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
 
-       ret = -ENODEV;
        if (ring->irq_get(ring)) {
                DRM_WAIT_ON(ret, ring->irq_queue, 3 * DRM_HZ,
                            READ_BREADCRUMB(dev_priv) >= irq_nr);
                ring->irq_put(ring);
-       }
+       } else if (wait_for(READ_BREADCRUMB(dev_priv) >= irq_nr, 3000))
+               ret = -EBUSY;
 
        if (ret == -EBUSY) {
                DRM_ERROR("EBUSY -- rec: %d emitted: %d\n",