radeon: Stop the ttm workqueue while reclocking

The ttm bo workqueue may touch objects while we're reclocking, so make
sure it's blocked until we're done.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_pm.c

@@ -460,9 +460,11 @@ bool radeon_pm_debug_check_in_vbl(struct radeon_device *rdev, bool finish)
 static void radeon_pm_idle_work_handler(struct work_struct *work)
 {
 	struct radeon_device *rdev;
+	int resched;
 	rdev = container_of(work, struct radeon_device,
 				pm.idle_work.work);
 
+	resched = ttm_bo_lock_delayed_workqueue(&rdev->mman.bdev);
 	mutex_lock(&rdev->ddev->struct_mutex);
 	mutex_lock(&rdev->pm.mutex);
 	if (rdev->pm.state == PM_STATE_ACTIVE) {
@@ -509,6 +511,7 @@ static void radeon_pm_idle_work_handler(struct work_struct *work)
 	}
 	mutex_unlock(&rdev->pm.mutex);
 	mutex_unlock(&rdev->ddev->struct_mutex);
+	ttm_bo_unlock_delayed_workqueue(&rdev->mman.bdev, resched);
 
 	queue_delayed_work(rdev->wq, &rdev->pm.idle_work,
 					msecs_to_jiffies(RADEON_IDLE_LOOP_MS));