Re: [RFC PATCH 0/3] PM / Domains: Add support for devices that require multiple domains

From: Jon Hunter
Date: Mon Mar 13 2017 - 10:29:42 EST


Hi Geert,

On 13/03/17 14:19, Geert Uytterhoeven wrote:
> Hi Jon,
>
> On Mon, Mar 13, 2017 at 3:09 PM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>> On 13/03/17 11:45, Ulf Hansson wrote:
>>> +BjÃrn
>>>
>>> On 13 March 2017 at 10:37, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>>>> Looks like there is still some interest/needs in/for this. Any thoughts
>>>> on how we can move this forward?
>>>
>>> At the Linaro Connect last week, I was talking to BjÃrn, Rajendra and
>>> Stephen more about these related issues.
>>>
>>> It definitely seems like we need to progress with this somehow,
>>> meaning we need a solution for being able to associate a device with
>>> more than one PM domain. In that context, I don't think genpd based on
>>> its current design, is a good fit to solve the problem.
>>>
>>> Instead I think we need something entirely new (perhaps some code can
>>> be borrowed from genpd), which is more similar to the clock/regulator
>>> framework. In other words, what you also were suggesting in a earlier
>>> reply.
>>> In this way, the driver/subsystem gains full flexibility of managing
>>> its device's PM domains, which seems like the best future-proof
>>> solution.
>>
>> I agree, I think that that would give us the most flexibility to handle
>> whatever scenario. However, I was thinking that we could still use the
>> genpd core to register pm-domains with and control. My thought was to
>> allow devices to have a bindings with multiple pm-domains ...
>>
>> dev-xyz {
>> ...
>> power-domains = <&domain-a>, <&domain-b>;
>> };
>>
>> Then in the genpd core we do having something like ...
>>
>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>> index e697dec9d25b..d1ae6ddf4903 100644
>> --- a/drivers/base/power/domain.c
>> +++ b/drivers/base/power/domain.c
>> @@ -2026,6 +2026,15 @@ int genpd_dev_pm_attach(struct device *dev)
>> "samsung,power-domain", 0);
>> if (!pd_args.np)
>> return -ENOENT;
>> + } else if (ret > 1) {
>> + /*
>> + * If there are more than one PM domain defined for a device,
>> + * then these need to be manually controlled by the device
>> + * driver because the genpd core cannot bind a device with
>
> Which device driver?
> The driver for the device that belongs to multiple PM domains?

Yes, exactly. So maybe I would need to say ... "manually controlled by
the driver for *this* device ..."

Jon

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