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

Nigel Cunningham
2007-02-11T22:49:05Z

Hi.

On Sun, 2007-02-11 at 12:13 +0000, Matthew Garrett wrote:
> On Sun, Feb 11, 2007 at 07:54:04AM +0100, Willy Tarreau wrote:
>
> > 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.

I think we have it backwards there. Power management support for a
driver should always start with the driver itself. If there's a generic
routine that can be used for the bus, the driver should explicitly set
the routine to the generic routine.

Regards,

Nigel