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From: Kevin Hilman <khilman@baylibre.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Dave Gerlach <d-gerlach@ti.com>, Nishanth Menon <nm@ti.com>,
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        Jon Hunter <jonathanh@nvidia.com>
Subject: Re: [PATCH 3/3] soc: ti: Add ti_sci_pm_domains driver
Organization: BayLibre
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Date: Thu, 08 Sep 2016 10:38:27 -0700
In-Reply-To: <CAPDyKFo0Cb90BbY7ra6VDjb5frC5=VtmE3V6tDK=VosfPmod7Q@mail.gmail.com>
        (Ulf Hansson's message of "Thu, 8 Sep 2016 11:27:52 +0200")
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Ulf Hansson <ulf.hansson@linaro.org> writes:

> [...]
>
>>
>> One more idea...
>>
>> Since you don't really have a domain (a group of devices), what you
>> really have is each device having an independent power switch, so as Ulf
>> suggested, what you really need is for all the devices to share the same
>> set of runtime PM callbacks that call SCI.  The only difference is the
>> unique ID.
>>
>> Rather than using all of genpd, you could also just use a pm_domain
>> which is what genpd is built on top of (and also omap_device, which
>> you're probably familiar with also.)
>
> Even if this would work as well, the downside would be that you need
> to re-invent the parts related to the DT parsing, the probing/removal
> and attaching/detaching of the device to the PM domain.
>
> You probably don't want to go there... :-)

All you'd need to read from DT would be the device-specific ID for
TI-SCI, and that could be done at bind time with a notifier.  The, in
that same notifier, if a TI-SCI ID exists, it would get added to the
pm_domain.

Anyways, your original proposal is much preferred if it can work.  I'm
just throwing out another option because I really don't like one genpd
per device.

Kevin