change_volume(urb_out, line6pcm->volume_playback, bytes_per_frame);
- if (line6pcm->prev_fbuf != 0) {
+ if (line6pcm->prev_fbuf != NULL) {
#ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
if (line6pcm->flags & MASK_PCM_IMPULSE) {
create_impulse_test_signal(line6pcm, urb_out,