[PATCH v2 18/20] mmc: sdio: enable a default power off mode of the card

[Ohad Ben-Cohen]

On Sun, Jul 25, 2010 at 4:56 PM, Nicolas Pitre <nico at fluxnic.net> wrote:
> On Sun, 25 Jul 2010, Ohad Ben-Cohen wrote:
>
>> On Thu, Jul 22, 2010 at 2:35 PM, Roger Quadros <roger.quadros at nokia.com> wrote:
>> > On 07/21/2010 08:33 PM, ext Ohad Ben-Cohen wrote:
>> >>
>> >> Add support for an SDIO device to stay powered off even without
>> >> the presence of an SDIO function driver. A host should explicitly
>> >> ask for it by means of MMC_CAP_DONT_POWER_CARD, and the SDIO
>> >> function driver should know it needs to call sdio_claim_power
>> >> before accessing the device.
>> >>
>> >> Signed-off-by: Ohad Ben-Cohen<ohad at wizery.com>
>> >
>> > Shouldn't this be the default behaviour? If there is no function driver for
>> > any of the functions of the card, then sdio core shold power off the card.
>> >
>> > I don't see a need for a special capability flag for this.
>> >
>> > in fact MMC_CAP_DONT_POWER_CARD does not seem like an mmc host's capability
>>
>> Totally agree.
>>
>> I didn't want to change the current behavior of the cards/funcs so I
>> looked for a way to explicitly power down only specific cards.
>>
>> Alternatively we could power down all cards at the end
>> mmc_attach_sdio, and then power them up selectively in sdio_bus_probe,
>> just before calling probe. If the probe succeeds, the function driver
>> takes over. If the probe fails, we can power them down again.
>
> Exactly!

Ok, v3 is on the way :)

(featuring no special host CAP, fix locking issues, and power down
unclaimed cards also on resume)