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SubjectRe: [linux-pm] [RFC][PATCH 1/2] Introduce struct syscore_ops and related functionality
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On Thursday, March 10, 2011, Alan Stern wrote:
> On Thu, 10 Mar 2011, Rafael J. Wysocki wrote:
>
> > Some subsystems need to carry out suspend/resume and shutdown
> > operations with one CPU on-line and interrupts disabled. The only
> > way to register such operations is to define a sysdev class and
> > a sysdev specifically for this purpose which is cumbersome and
> > inefficient. Moreover, the arguments taken by sysdev suspend,
> > resume and shutdown callbacks are practically never necessary.
> >
> > For this reason, introduce a simpler interface allowing subsystems
> > to register operations to be executed very late during system suspend
> > and shutdown and very early during resume in the form of
> > strcut syscore_ops objects.
>
> ...
>
> > Index: linux-2.6/drivers/base/syscore.c
> > ===================================================================
> > --- /dev/null
> > +++ linux-2.6/drivers/base/syscore.c
>
> It's true that the existing sys.c file lies in drivers/base; this is
> presumably because it handles a bunch of class-related registration
> stuff. Now you're getting rid of all that, leaving just the
> power-related operations, so doesn't it make more sense to put this
> file in drivers/base/power?

I didn't, because shutdown() doesn't really belong in there (well, depending).

> > +/**
> > + * syscore_suspend - Execute all the registered system core suspend callbacks.
> > + *
> > + * This function is executed with one CPU on-line and disabled interrupts.
> > + */
> > +int syscore_suspend(void)
> > +{
> > + struct syscore_ops *ops;
> > +
> > + list_for_each_entry_reverse(ops, &syscore_ops_list, node)
> > + if (ops->suspend) {
> > + int ret = ops->suspend();
> > + if (ret) {
> > + pr_err("PM: System core suspend callback "
> > + "%pF failed.\n", ops->suspend);
> > + return ret;
>
> If an error occurs, you need to go back and resume all the things that
> were suspended. At least, that's what the code in sysdev_suspend does.

Right, thanks a lot!

> > + }
> > + }
> > +
> > + return 0;
> > +}

Rafael


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