[PATCH v3 1/3] base: power: Add generic OF-based power domain look-up

[Ulf Hansson]

On 28 April 2014 19:35, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 04/23/2014 10:46 AM, Tomasz Figa wrote:
>> This patch introduces generic code to perform power domain look-up using
>> device tree and automatically bind devices to their power domains.
>> Generic device tree binding is introduced to specify power domains of
>> devices in their device tree nodes.
>>
>> Backwards compatibility with legacy Samsung-specific power domain
>> bindings is provided, but for now the new code is not compiled when
>> CONFIG_ARCH_EXYNOS is selected to avoid collision with legacy code. This
>> will change as soon as Exynos power domain code gets converted to use
>> the generic framework in further patch.
>
>> diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
>
>> +==Power domain consumers==
>> +
>> +Required properties:
>> + - power-domain : A phandle and power domain specifier as defined by bindings
>> +                  of power controller specified by phandle.
>
> It seems quite likely that a single logical device could have components
> in multiple power domains. Consider an HDMI controller with different
> power domains for the HDMI core, CEC communication, DDC/I2C
> communication, and the I/O pads, with no clear separation between those
> two components of the module (no separate register spaces, but the
> bits/registers are interleaved all together).
>
> As such, I think that rather than a "power-domain" property, we need a
> pair of "power-domains", and "power-domain-names" properties, and
> preferably with mandatory usage of name-based lookups, rather than
> allowing a random mix of name-based and index-based lookups like we have
> with some existing resource bindings.

Each struct device have only one dev_pm_domain pointer, thus a device
are not able to reside in more than one power domain.

Therefore I doubt this will be very useful, unless I missed your point. :-)

Kind regards
Ulf Hansson