Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD card is inserted]

Alan Stern
2008-02-25T20:01:03Z

On Mon, 25 Feb 2008, Pierre Ossman wrote:

> > What do you think of the patch attached to comment #40 in the Bugzilla
> > entry?
> >
>
> Looks ok. As long as those two synchronization points are guaranteed,
> then I'm happy.

Maybe a better approach would be to leave the workqueue unfreezable,
and keep cancel_delayed_work_sync() in mmc_suspend_host(). It would
then be necessary to add a test to verify, if there is a card attached,
that the card is indeed suspended. After all, it's possible that the
cancel_delayed_work_sync() ended up waiting for a job already running
on the workqueue to register a new card! (The same would be true even
with flush_scheduled_work.)

Also, as a bit of defensive programming, it might be a good idea to add
a "suspended" flag to the mmc_host structure. If mmc_rescan() sees
that the flag is set then it should return immediately. This would
protect against host drivers that aren't careful to disable detect
IRQs before calling mmc_suspend_host().

Alan Stern