> Hi, all.
>    SPI seems to be a reasonable local bus for future stuff. Low pin count,  
> reasonable bitrate, a fair and growing number of SDIO peripherals, and SD  
> cards are a reasonable way of adding storage.
>    The EP9302 on Airship only supports the one-bit SDIO interface, but  
> PXA27x on Balloon3 has the full thing.
>    Using SPI as the link between the propellor(s) on Airship and the EP9302  
> has charm - the propellor can be the master, which will allow us to run  
> the bus as hard as possible (since propellor has no hardware SPI, it ought  
> to generate the clock).
>    Is there support in the Linux flavours we're tending to use for SD and  
> SDIO stuff?
There is linux support for MMC that all SD cards must support. I am unclear 
whether SDIO can exist in extended MMC mode or not. The problem is legal 
stuff with SD protocols.

See 
http://help.lockergnome.com/linux/RFC-MMC-driver-model-ftopict365237.html 
for some SDIO integration chatter.

Current stock kernel has MMC and MMC on MMC/SD/SDIO controllers but I am 
unclear if this extends to SDIO support. I think it doesn't.

See http://www.arasan.com/html4pdf/sdio_nex_driver_overview.php for a 
commercial linux implementation on its own hardware and a review at 
http://linuxdevices.com/news/NS3979314345.html

Nick

> 
> Steve
> 
> 
> 
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