SDIO multiplexing

andrzej zaborowski balrogg at
Mon Apr 28 13:51:03 CEST 2008

On 28/04/2008, Andy Green <andy at> wrote:
>  Hash: SHA1
>  Somebody in the thread at some point said:
>  | On 28/04/2008, Werner Almesberger <werner at> wrote:
>  |>  > Basically a form of SDIO multiplexing.
>  |>  > Other options would be SPI.
>  |>
>  |>
>  |> We once asked Samuel about SPI, and he said that it would be slower,
>  |>  but still good enough. (In real life, the theoretically possible
>  |>  maximum speed is rarely reached anyway.)
>  |>
>  |>  Without digging through the Atheros driver, I don't know how much work
>  |>  it would be to put it on SPI. If the abstraction is clean, it could be
>  |>  very simple. If not, a pain.
>  |
>  | You'd need to also adapt the mmc/sd stack in linux/drivers/mmc/ to use
>  | the SPI mode because it's not supported by linux at the moment.  In
>  | this mode different MMC commands are allowed and the state machine is
>  | a little different.  There may already be patches available somewhere.
>  I think we propose to just move WLAN interface to native SPI, leave MMC
>  / SD using native SDIO interface from S3C2442.  So no need for
>  considering the SPI mode of MMC commands.

Oops sorry then. Multiplexing made me think of multiplexing on the mmc
bus, which also is an allowed configuration.


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