On Thu, 2009-02-26 at 13:20 -0800, Arve Hjønnevåg wrote:

On Thu, Feb 26, 2009 at 12:57 PM, Benjamin Herrenschmidt
[off-list ref] wrote:

quoted

On Thu, 2009-02-26 at 12:34 -0800, Arve Hjønnevåg wrote:

quoted

That is enough for drivers that use wakelocks to abort suspend (if I
fix the wakelock code to not use a platform device as its last abort
point). It is not enough if you don't have wakelocks, since the
interrupt can occur after suspend_late has been called and the driver
has no way to abort suspend.

I still don't quite see how you deal with the race anyway. Ie. Even
without Rafael patch, what if the interrupt occurs after your sysdev
suspend ?

After local_irq_disable has been called, the interrupt will no longer
be cleared by Linux when it occurs. This means that is still pending
when you get to the low level suspend code which will prevent suspend.

Ok so you want this interrupt to stay pending at the PIC level ? So just
marking it so the kernel doesn't disable it should do the trick.

quoted

In general, unless they are level sensitive, wakeup interrupts tend to
always be somewhat racy.

They don't have to be. If you have a separate hardware component that
tracks wakeup interrupts, you need to start this before you stop the
main interrupt controller. If any interrupts are pending at this time
you abort suspend. After a wakeup you do the reverse.

Right but then you can start this earlier and there is no problem. But
if you do want the interrupt to remaining pending in the PIC, then you
probably need to set that magic flag so we don't disable it, that should
do the trick just fine no ?

It's hard to tell without more detailed HW specs of course...

Ben.


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