Re: [PATCH v5 08/11] arm: dts: qcom: Add #power-domain-cells property

[Rajendra Nayak <rnayak@codeaurora.org>]

On 04/24/2015 09:13 PM, Ulf Hansson wrote:
> On 24 April 2015 at 12:55, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>> On 04/24/2015 03:15 PM, Ulf Hansson wrote:
>>>
>>> On 14 April 2015 at 15:12, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>>>>
>>>> msm8974 has gcc and mmcc nodes, and apq8084 has a gcc node which
>>>> implement gdsc powerdomains. Add the #power-domain-cells property
>>>> to them.
>>>>
>>>> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
>>>> ---
>>>>    arch/arm/boot/dts/qcom-apq8084.dtsi | 1 +
>>>>    arch/arm/boot/dts/qcom-msm8974.dtsi | 2 ++
>>>>    2 files changed, 3 insertions(+)
>>>>
>>>> diff --git a/arch/arm/boot/dts/qcom-apq8084.dtsi
>>>> b/arch/arm/boot/dts/qcom-apq8084.dtsi
>>>> index 1f130bc..55c281c 100644
>>>> --- a/arch/arm/boot/dts/qcom-apq8084.dtsi
>>>> +++ b/arch/arm/boot/dts/qcom-apq8084.dtsi
>>>> @@ -183,6 +183,7 @@
>>>>                           compatible = "qcom,gcc-apq8084";
>>>>                           #clock-cells = <1>;
>>>>                           #reset-cells = <1>;
>>>> +                       #power-domain-cells = <1>;
>>>
>>>
>>> So the PM domain will be apart of the clock-controller. That's a bit
>>> odd, but I guess the hardware is like that!?
>>
>>
>> Yes, the gdscs are all part of GCC controller.
>>
>>>
>>> Anyway, what I fail to understand from this patchset is who will be
>>> the actual consumer of the PM domain? In other words, what devices
>>> will hold the below property in its DT node?
>>>
>>> power_domains = <phandle index>;
>>>
>>> This is needed for genpd to have the device at probe time, attached to
>>> its PM domain.
>>
>>
>> Any device which belongs to the collapsible power domain (gdsc)
>> Examples are graphics, camera, video encode/decode block (venus) etc
>
> Then I expect those drivers to deploy runtime PM (if not already) and
> thus gdsc's PM domain will come into play.

Most of these drivers aren;t upstream yet. And one of the reasons I am
trying to get gdsc support upstream is so these drivers can then be
pushed upstream, with runtime support.

>
> But how will that relate to the GCC controller?
>
> For example when the gdsc's PM domain is about to be powered off,
> since all the devices within it has be runtime PM suspended. What
> happens with the GCC controller then?

I don;t seem to completely understand what you are asking. Are you
asking if the GCC controller itself is part of a collapsible power
domain?

>
> Kind regards
> Uffe
>

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