Re: [linux-pm] [patch update 2 fix] PM: Introduce core framework for run-time PM of I/O devices

Alan Stern
2009-06-22T14:16:45Z

On Sun, 21 Jun 2009, Rafael J. Wysocki wrote:

> > Seriously, there _are_ places where drivers get bound to device before
> > those devices are registered. This happens for example in USB when a
> > bunch of related interfaces are present in the same physical device.
> > When the first interface is registered, its driver binds itself to all
> > the others even though they haven't been registered yet.
>
> Well, the suspend functions could be protected against that under the
> assumption that no suspend is possible for resume_counter = 0 (then, the "good
> to go" value would be -1).
>
> Still, the resume functions start from acquring a spinlock, which is not going
> to work if that spinlock is uninitialized.

The initialization needs to be improved. Most of the code in
pm_runtime_init() should be called from device_pm_init(), and the rest
should be moved into a separate pm_runtime_add() routine to be called
from device_pm_add().

One of the things pm_runtime_add() could do is change the status from
RPM_UNREGISTERED to RPM_ACTIVE.

Alan Stern