linux-kernel - Re: [PATCH 6/9] ARM: tegra: Export tegra_powergate_power

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Message-ID: <53A1B252.1030204@wwwdotorg.org>
Date:	Wed, 18 Jun 2014 09:37:54 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Peter De Schrijver <pdeschrijver@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>
CC:	Mikko Perttunen <mperttunen@...dia.com>,
	"tj@...nel.org" <tj@...nel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>
Subject: Re: [PATCH 6/9] ARM: tegra: Export tegra_powergate_power_on

On 06/18/2014 06:18 AM, Peter De Schrijver wrote:
> On Tue, Jun 17, 2014 at 11:51:20PM +0200, Thierry Reding wrote:
>> * PGP Signed by an unknown key
>>
>> On Tue, Jun 17, 2014 at 05:01:46PM +0300, Peter De Schrijver wrote:
>>> On Tue, Jun 17, 2014 at 02:13:15PM +0200, Thierry Reding wrote:
>>>>> Old Signed by an unknown key
>>>>
>>>> On Mon, Jun 16, 2014 at 04:01:02PM -0600, Stephen Warren wrote:
>>>>> On 06/04/2014 05:32 AM, Mikko Perttunen wrote:
>>>>>> This symbol needs to be exported to power on rails without using
>>>>>> tegra_powergate_sequence_power_up. tegra_powergate_sequence_power_up
>>>>>> cannot be used in situations where the driver wants to handle clocking
>>>>>> by itself.
>>>>>
>>>>> Thierry, are you OK with this change?
>>>>
>>>> I would've preferred tegra_powergate_sequence_power_up() to be used
>>>
>>> I don't think the current tegra_powergate_sequence_power_up() API is very well
>>> defined though. I don't think the clocks and resets required by the sequence
>>> should be provided by the driver. For one, there can be several clocks and
>>> resets that need to be controlled for a single domain.
>>
>> Do you have any suggestions for what the API should look like? Even if
>> we plan to move to some different API, I think there's some advantage in
>> using it consistently if for no other reason than to make it easier to
>> replace occurrences later on.
>>
> 
> I think the API should only have the domain ID as input so:
> 
> int tegra_powerdomain_on(int id) 
> 
> /*
>  * Prerequisites: domain is off
>  * Result: domain is on, clocks of the modules in the domain are off, modules are in reset
>  */
> 
> int tegra_powerdomain_off(int id)
> 
> /*
>  * Prerequisites: all clocks of the modules in the domain are off
>  * result: domain is off
>  */

That doesn't make sense; the PMC doesn't have access to the clock and
reset IDs - that's why the API requires them to be passed in.

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