drm/i915: Do the fallback non-IRQ wait in ring throttle, too.

commit 7ea29b13 upstream.

As a workaround for IRQ synchronization issues in the gen7 BLT ring,
we want to turn the two wait functions into polling loops.
Signed-off-by: Eric Anholt <eric@anholt.net>
Tested-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/i915/i915_gem.c

@@ -3312,6 +3312,10 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 
 			if (ret == 0 && atomic_read(&dev_priv->mm.wedged))
 				ret = -EIO;
+		} else if (wait_for(i915_seqno_passed(ring->get_seqno(ring),
+						      seqno) ||
+				    atomic_read(&dev_priv->mm.wedged), 3000)) {
+			ret = -EBUSY;
 		}
 	}