Suspend/resume without bringing down SDIO

[Chris Ball]

Hi,

   > Is there any story behind that why all cards must be powered down
   > during suspend?

Just that the common case for SD cards is that they contain filesystems,
and those cards should be unmounted and powered off during suspend
because there's no point in leaving them on, and it can be dangerous
to the filesystem to do so.  The Linux SD stack is still new enough
that it hasn't yet grown the ability to differentiate cards that
should stay powered in suspend and cards that shouldn't.

(That said, see Nicolas Pitre's recent patches on the linux-mmc@ list,
which attempt to solve this SDIO problem.)

   > There're real cases that some SDIO WiFi cards indeed DO NOT like
   > to be powered down during suspend, e.g they want to enter deep
   > sleep.

Yes.

- Chris.
-- 
Chris Ball   <cjb at laptop.org>
One Laptop Per Child