On Sat, Feb 15, 2014 at 01:18:02PM +0100, Arnd Bergmann wrote:

If a wlan adapter has both SPI and SDIO front-ends, the external
dependencies (reset, clock, voltage, ...) will be the same, and
from the kernel perspective the main difference is that SPI cannot
be probed at all, while SDIO can be probed as long as the device
is powered on already.

Remember that MMC/SD/SDIO cards can be driven by either a MMC host
interface, or a SPI interface.  Both are probe-able.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".