The ALSA source shipped with potato (yes even r2) has a compile error when built against the 2.2.81pre21 kernel source. Fortunately, it's easy to fix.
In the alsa source include directory, you'll find a file drivers.h. Edit this file. Search for the word "wait". The first occurance is in a #ifndef KERNEL_2_3 test (I'm not at the Linux machine now so the define might not be exact). Change the #ifndef line to "#if 0". It should compile fine after that. Cheers, dar