nv_wr32(dev, 0x100c80, (engine << 16) | 1);
if (!nv_wait(dev, 0x100c80, 0x00000001, 0x00000000))
NV_ERROR(dev, "vm flush timeout: engine %d\n", engine);
nv_wr32(dev, 0x100c80, (engine << 16) | 1);
if (!nv_wait(dev, 0x100c80, 0x00000001, 0x00000000))
NV_ERROR(dev, "vm flush timeout: engine %d\n", engine);