[PATCH v2 1/3] OMAP: PM: initial runtime PM core support

[Grant Likely]

On Fri, Jun 25, 2010 at 4:46 PM, Kevin Hilman
<khilman at deeprootsystems.com> wrote:
> Grant Likely <grant.likely at secretlab.ca> writes:
>
>> Another way to look at the problem is that these runtime
>> customizations are kind of a property of the parent device (the bus,
>> not the bus_type).  Would it make sense for parent devices to have
>> runtime ops to perform for each child that is suspended/resumed?  That
>> would make it simple to register another device that implements the
>> bus behaviour and attach it at runtime instead of compile time.
>
> Maybe I didn't fully understand your idea, but the problem here is
> devices do not have dev_pm_ops.  Only busses, classes, and types have
> dev_pm_ops.

Sorry, I mistyped.  What I meant was for the parent device's
device_driver to be able to have a set of child dev_pm_ops; but I'm
wading into territory (power management) I'm not particularly familiar
with, and that might be making things far too complex.

> Though I'm horribly unfamiliar with the intended usage of 'struct
> device_type', an interesing discovery is that dev->type also has
> dev_pm_ops, and it takes precedence over the bus type in the
> suspend/resume.  IOW, when suspending, when deciding which dev_pm_ops to
> use, it checks class, type, then bus in that order.

So I guess my suggestion above boils down to somehow inserting
"parent" between type and bus in that list.

> I need to explore this 'type' feature a little more, but using that or
> the 'class' might be another way to have custom PM ops for certain
> platform_devices.

Should maybe start cc'ing Greg and linux-kernel/linux-pm in this discussion.

g.