On newer RME cards like RayDAT and AIO, the lower bound is 32 samples per period in contrast to 64 samples as seen on older cards. We hence lower period_bytes_min to 32 * 4. Four bytes per sample. Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>