Re: [linux-pm] [RFC][PATCH][1/8] PM: Rework handling of interrupts during suspend-resume (rev. 5)

Linus Torvalds
2009-03-08T17:21:21Z

On Sat, 7 Mar 2009, Alan Stern wrote:
>
> You didn't answer my question. Why bother to distinguish between
> "wake-up" interrupts and non-"wake-up" interrupts?
>
> In other words, why not simply abort the suspend if IRQ_PENDING is set
> for _any_ interrupt during sysdev_suspend()?

.. because some drivers might not actually shut down the hardware until
they get to "suspend_late"? If even then, for that matter - a driver may
simply not care, knowing that the hardware will be powered off, and will
be re-initialized at resume.

The thinking that you have to shut your hardware down at "->suspend()"
time is a _disease_. There are literally classes of hardware out there
where that would be an outright _bug_, like for a PCI bridge device. For
many devices, "suspend()" has to be the phase where you shut down the
_external_ stuff (eg for a disk controller, it's when you'd flush and stop
your disks), but the controller itself may well be alive until later.

Linus