Re: [PATCH] Re: NAK new drivers without proper power management?

Pavel Machek
2007-02-11T21:10:38Z

Hi!

> > > instead of modifying all drivers to explicitly state that they don't support
> > > it, we should start with a test of the NULL pointer for .suspend which should
> > > mean exactly the same without modifying the drivers. I find it obvious that
> > > a driver which does provide a suspend function will not support it. And if
> > > some drivers (eg /dev/null) can support it anyway, it's better to change
> > > *those* drivers to explicitly mark them as compatible.
> >
> > No, that doesn't work. In the absence of suspend/resume methods, the PCI
> > layer will implement basic PM itself. In some cases, this works. In
> > others, it doesn't. There's no way to automatically determine which is
> > which without modifying the drivers.
>
> Then change the PCI layer to do the basic PM only for known compatible
> drivers, and modify only the known-compatible drivers to mark them
> explicitly compatible. IMHO, it generally is a bad idea to require that
> any driver explicitly states what it *does not* support. It's the reason
> why users encounter problem on new features with old drivers. For instance,
> do you know if the old ISA NE2000 driver breaks suspend ? I don't know,
> but I would at least expect it not to support it by default. It's best
> to announce what *is* supported and consider everything unimplemented
> otherwise explicitly stated.

Actually, ne2k driver is okay. ne2k cards are notoriously buggy, so it
responds with "****, that damn card has just locked up again, lets
reset it". Ok, it takes timeout to realize card is "locked up",
so it could be improved...

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html