/sys/.../power/state Re: [linux-usb-devel] error to be returned while suspended

Pavel Machek
2006-10-08T19:41:37Z

Hi!

> > > The power management functions without
> > > timeout are also exported. For other power control features like
> > > cpu frequency considerable effort has been made to export them to
> > > user space.
> >
> > Yes, and many of us use the much lighter weight kernel based control
> > models by preference.   Why waste hundreds of Kbytes of userspace for
> > a daemon when a few hundred bytes of kernel code can implement a
> > better and more reactive kernel policy for cpufreq?
>
> That's an important aspect. How about implementing autosuspend
> first and keeping the sysfs-based suspension for now? If autosuspend

Current sysfs-based suspension allows people to do bad stuff to
drivers, like confusing them, oopsing them, etc. It is so broken that
it can not be fixed. (When I suspend my USB this way, I end up with
dead USB. When I suspend my sound card, I get any soundcard users in
unrecoverable D state.)

Now... you can prove me wrong, but that likely means auditing all the
drivers with suspend() and/or resume() methods. I'm not prepared to do
that work... are you?
Pavel
--
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