linux-kernel - Re: [PATCH v2 3/3] firmware: scpi: add device power domain support using genpd

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Message-ID: <5763B6FF.2040105@arm.com>
Date:	Fri, 17 Jun 2016 09:38:23 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	"Jon Medhurst (Tixy)" <tixy@...aro.org>
Cc:	Sudeep Holla <sudeep.holla@....com>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Kevin Hilman <khilman@...nel.org>
Subject: Re: [PATCH v2 3/3] firmware: scpi: add device power domain support
 using genpd



On 17/06/16 09:19, Jon Medhurst (Tixy) wrote:
> On Thu, 2016-06-16 at 18:59 +0100, Sudeep Holla wrote:
>>
>> On 16/06/16 18:47, Jon Medhurst (Tixy) wrote:
>>> On Thu, 2016-06-16 at 11:38 +0100, Sudeep Holla wrote:
>>> [...]
>>>> +enum scpi_power_domain_state {
>>>> +	SCPI_PD_STATE_ON = 0,
>>>> +	SCPI_PD_STATE_OFF = 3,
>>>> +};
>>>
>>> The SCPI doc defines the meaning of these numbers (0 and 3) in the 'Juno
>>> specifics' chapter. So does these values need to come from device-tree
>>> to allow for other hardware or SCP implementations?
>>>
>>
>> Ah unfortunately true :(. I had not noticed that. But I would like to
>> check if this can be made as part of the standard protocol. Adding such
>> details to DT seems overkill and defeat of the whole purpose of the
>> standard protocol.
>
> Well. it seems to me the 'standard protocol' is whatever the current
> implementation of ARM's closed source SCP firmware is. It also seems to
> me that people are making things up as they go along, without a clue as
> to how to make things generic, robust and future proof.

Totally agree. There's an effort to come up with more standard version
of this involving partners/users soon. It's still under discussion and
the aim is to make it as good as PSCI. Let's see where it goes...

-- 
Regards,
Sudeep