Re: [linux-pm] [PATCH] Fix the outstanding issue with hangs on insert/removal of mmc cards

[David Brownell <david-b@pacbell.net>]

--- On Fri, 6/11/10, Maxim Levitsky <maximlevitsky@gmail.com> wrote:
> After thinking a lot about how to fix properly the hangs
> caused by
> insert/removal of mmc card during suspend/resume, and default behavior
> of not trusting the card persistence over suspend,

Right; there are two types of driver:  ones
that can correctly report whether the card
has been removed ... and ones that can't  That
default behavior presumes the latter. 

The MMC/SD framework doesn't know about these
two types

(For
reference:  the easy way to do the former involves
setting up the GPIO used for card detect as a
(wakeup?) IRQ source.

> First of all there are 2 types of removal possible. First
> one happens
> when system detects that some device is gone. At that point
> there is
> really no point in syncing it.

One suggestion was syncing before suspend...
but that would require coordinating the
block layer and PM framework.  That seems
like it'd be generally a wise thing to do;
no point in losing the write cache, ever.


> The other type of removal is controlled removal, usually on user  request.