[RFC PATCH 1/8] PM / Domains: Add new helper functions for device-tree

[Ulf Hansson]

On 22 June 2016 at 17:22, Jon Hunter <jonathanh at nvidia.com> wrote:
>
> On 22/06/16 16:08, Ulf Hansson wrote:
>> On 22 June 2016 at 16:58, Jon Hunter <jonathanh at nvidia.com> wrote:
>>> Hi Ulf,
>>>
>>> On 04/03/16 11:23, Jon Hunter wrote:
>>>> Ideally, if we are returning a reference to a PM domain via a call to
>>>> of_genpd_get_from_provider(), then we should keep track of such
>>>> references via a reference count. The reference count could then be used
>>>> to determine if a PM domain can be safely removed. Alternatively, it is
>>>> possible to avoid such external references by providing APIs to access
>>>> the PM domain and hence, eliminate any calls to
>>>> of_genpd_get_from_provider().
>>>>
>>>> Add new helper functions for adding a device and a subdomain to a PM
>>>> domain when using device-tree, so that external calls to
>>>> of_genpd_get_from_provider() can be removed.
>>>
>>> While we are at it, does it make sense to add helpers for
>>> of_genpd_remove_device/subdomain() as well? Seems that these could be
>>> useful for doing the inverse when cleaning up.
>>
>> I would prefer if we could avoid adding new APIs until we really see
>> the need for it.
>>
>> Moreover, I would like to avoid us adding OF specific APIs, unless
>> those can be really justified.
>> Hope that made sense.
>
> Yes makes sense. However, after this series, the
> pm_genpd_remove_device/subdomain really become provider only APIs
> because clients can no longer get access to the genpd struct. Although
> today none of the users of the new of_genpd_add_device/subdomain do any
> clean-up on failure, it is possible that someone may. Therefore, I was
> thinking that we should have a way for a client to remove a subdomain or
> device it has added.
>
> Does that make sense? I guess we could always add those as needed.
>
> I am looking at a use-case for usb where we are populating the
> pm-domains at runtime and we may need to clean-up on failure. However, I
> can always wait to add more APIs until we really need them.

You may very well be right that these will be needed.

How about posting those patches as separate change and on top of the
series. Then we can decide if we want to pick them now or later.

>
> Let me know what you think about my response to patch 6/8.

I am on it.

Kind regards
Uffe