Re: [PATCH v2] Add suspend/resume for HPET

Linus Torvalds
2007-03-31T16:59:59Z

On Sat, 31 Mar 2007, Thomas Gleixner wrote:
>
> Right, but clock - sources/events need to be extremly late suspended and
> early resumed. How can we ensure this ?

Make them be at the top of the device tree by adding them early. That's
the whole point of the device tree after all - we have an ordering that is
enforced by its topology, and that we sort by when things were added.

Right now the way things work is (iirc - somebody like Greg should
double-check me) is that we add all devices to the power list at
device_add() time by traversing the devices fromt he root all the way out,
and doing a device_add() which does a device_pm_add(), which in turn adds
it to the power-management list - so that the list is always topologically
sorted.

So the only thing that needs to be done is to make sure that we add the
timer devices early during bootup - something we have to do *anyway*. If a
device is added early in bootup, that automatically means that it will be
suspended late, and resumed early - because we maintain that order all the
way through..

Linus