DRM_IOCTL_NR
[DRM_IOCTL_NR(ioctl)] = {.cmd = ioctl, .func = _func, .flags = _flags, .cmd_drv = 0}
[DRM_IOCTL_NR(DRM_##ioctl)] = {.cmd = DRM_##ioctl, .func = _func, .flags = _flags, .cmd_drv = DRM_IOCTL_##ioctl}
unsigned int nr = DRM_IOCTL_NR(cmd);
(nr == DRM_IOCTL_NR(DRM_IOCTL_DMA)) && dev->driver->dma_compat_ioctl)
if ((nr == DRM_IOCTL_NR(DRM_IOCTL_DMA)) && dev->driver->dma_ioctl)