[PATCH 8/9] PM / Domains: Add support for multi PM domains per device to genpd

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* genpd_dev_pm_attach_by_id() - Attach a device to one of its PM domain.
* @dev: Device to attach.
* @index: The index of the PM domain.

This naming and description is a bit misleading, because really it is not
attaching the device that is passed, but creating a new device to attach
a
PM domain to. So we should consider renaming and changing the description
and indicate that users need to link the device.

I picked the name to be consistent with the existing
genpd_dev_pm_attach(). Do you have a better suggestion?

Well, it appears to get more of a 'get' function and so I don't see why we
could not have 'genpd_dev_get_by_id()' and then we could have a
genpd_dev_put() as well (which would call genpd_dev_pm_detach).

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I agree, some details is missing to the description, let me try to
improve it. Actually, I was trying to follow existing descriptions
from genpd_dev_pm_attach(), so perhaps that also needs a little
update.

However, do note that, neither genpd_dev_pm_attach() or
genpd_dev_pm_attach_by_id() is supposed to be called by drivers, but
rather only by the driver core. So description may not be so
important.

In regards to good descriptions, for sure the API added in patch9,
dev_pm_domain_attach_by_id(), needs a good one, as this is what
drivers should be using.

OK. Same appears to apply here to the description as I mentioned above.
Still seems to be more of a 'get' than an attach. So I wonder if it should
be dev_pm_domain_get_by_id() instead?

Regarding "get" vs "attach", I suggest we continue to discuss that in
patch 9. Whatever is decided, $subject patch needs to follow.

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Finally, how is a PM domain attached via calling
genpd_dev_pm_attach_by_id()
detached?

Via the existing genpd_dev_pm_detach(), according to what I have
described in the change log. I clarify the description in regards to
this as well.

OK, so this bit is a to-do as that is not yet exposed AFAICT. I see that you
said 'although we need to extend it to cover cleanup of the earlier
registered device, via calling device_unregister().' So if we do this then
that would be fine.

Let me clarify the changelog. It's not a to-do, as it's already done
as part of $subject patch.

So I guess we are in agreement that we don't need another API to deal
with detach?

Kind regards
Uffe