Re: PATCH: PM / Runtime: Remove idle notification after failingsuspend (was: Re: [linux-pm] [PATCH] PM: add synchronous ...)

[Alan Stern]

On Sat, 9 Oct 2010, Rafael J. Wysocki wrote:

> From: Rafael J. Wysocki <rjw@xxxxxxx>
> Subject: PM / Runtime: Remove idle notification after failing suspend
> 
> If runtime suspend of a device fails returning -EAGAIN or -EBUSY,
> which means that it's safe to try to suspend it again, the PM core
> runs the runtime idle helper function for it.  Unfortunately this may
> lead to problems, for example for PCI devices whose drivers don't
> implement the ->runtime_idle() callback, because in that case the
> PCI bus type's ->runtime_idle() always calls pm_runtime_suspend()
> for the given device.  Thus, if it is automatically called by a
> driver's ->runtime_suspend() returning -EAGAIN or -EBUSY, it will
> cause the suspend to happen again possibly causing a busy loop to
> appear.  To avoid that, remove the idle notification after failing
> runtime suspend of a device altogether and let the callers of
> pm_runtime_suspend() repeat the operation if need be.
> 
> Reported-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>

This is fine as far as I'm concerned.

Alan Stern

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