kernelconfig_penguin

PIO (Programmed I/O) only

configname: CONFIG_B43LEGACY_PIO_MODE

Broadcom 43xx-legacy data transfer mode
└─> PIO (Programmed I/O) only

Only include Programmed I/O (PIO).
This reduces the size of the driver module, by omitting the DMA code.
Please note that PIO transfers are slow (compared to DMA).

Also note that not all devices of the b43legacy series support PIO.

You should use PIO only if DMA does not work for you.