+ pcm_devs - Number of PCM devices assigned to each card
+ (default = 1, up to 4)
+ pcm_substreams - Number of PCM substreams assigned to each PCM
+ (default = 8, up to 16)
+ hrtimer - Use hrtimer (=1, default) or system timer (=0)
+
+ When multiple PCM devices are created, snd-dummy gives different
+ behavior to each PCM device:
+ 0 = interleaved with mmap support
+ 1 = non-interleaved with mmap support
+ 2 = interleaved without mmap
+ 3 = non-interleaved without mmap
+