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SubjectRe: [PATCH 6/6 v2] arm: omap: usb: global Suspend and resume support of ehci and ohci
On Mon, 4 Jul 2011, Felipe Balbi wrote:

> sounds to me like a bug on pm runtime ? If you're calling
> pm_runtime_*_sync() family, shouldn't all calls be _sync() too ?

No. This was a deliberate design decision. It minimizes stack usage
and it gives a chance for some other child to resume before the parent
is powered down.

> > static int rpm_suspend(struct device *dev, int rpmflags)
> > __releases(&dev->power.lock) __acquires(&dev->power.lock)
> > {
> > .
> > .
> > .
> > no_callback:
> > .
> > .
> > .
> > /* Maybe the parent is now able to suspend. */
> > if (parent && !parent->power.ignore_children &&
> > !dev->power.irq_safe) {
> > spin_unlock(&dev->power.lock);
> >
> > spin_lock(&parent->power.lock);
> > rpm_idle(parent, RPM_ASYNC);
>
> to me this is bogus, if you called pm_runtime_put_sync() should should
> be sync too. Shouldn't it ?

No, it shouldn't.

> > spin_unlock(&parent->power.lock);
> >
> > spin_lock(&dev->power.lock);
> > }
> > This is the reason of directly calling the parent Runtime PM calls from
> > the children.
> > If directly calling Runtime PM APIs with parent dev-pointer isn't
> > acceptable,
> > this can be achieved by exporting wrapper APIs from the
> > parent and calling them from the chidren .suspend/.resume routines.
>
> Still no good, IMHO.

The real problem here is that you guys are trying to use the runtime PM
framework to carry out activities during system suspend. That won't
work; it's just a bad idea all round. Use the proper callbacks to do
what you want.

Alan Stern



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