Re: [PATCH] MMC Agressive clocking framework v6

[David Vrabel <david.vrabel@csr.com>]

On 29/10/2010 21:18, Linus Walleij wrote:
> This patch modifies the MMC core code to optionally call the
> set_ios() operation on the driver with the clock frequency set
> to 0 (gate) after a grace period of at least 8 MCLK cycles, then
> restore it (ungate) before any new request. This gives
> the driver the option to shut down the MCI clock to the MMC/SD
> card when the clock frequency is 0, i.e. the core has stated
> that the MCI clock does not need to be generated.

With SDIO cards, 1 bit mode needs to be set on the controller otherwise
many controllers cannot detect card interrupts.

Also some v2.00 SDIO cards in 4-bit mode will not generate card
interrupts unless they are clocked (the spec v2.00 doesn't require them
to be able to but v3.00 does).  I would suggest a white list of v2.00
cards that can generate interrupts asynchronousy.

David