linux-kernel - Re: [RFC PATCH] pwm: Add the concept of an "active" pinctrl

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Date:	Tue, 7 Oct 2014 13:30:58 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Thierry Reding <thierry.reding@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Chris Zhong <zyw@...k-chips.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Sonny Rao <sonnyrao@...omium.org>,
	"linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] pwm: Add the concept of an "active" pinctrl

Linus,

On Tue, Oct 7, 2014 at 6:15 AM, Linus Walleij <linus.walleij@...aro.org> wrote:
> On Thu, Sep 25, 2014 at 10:26 PM, Doug Anderson <dianders@...omium.org> wrote:
>> On Thu, Sep 25, 2014 at 12:31 AM, Linus Walleij
>> <linus.walleij@...aro.org> wrote:
>>> On Wed, Sep 24, 2014 at 1:17 AM, Doug Anderson <dianders@...omium.org> wrote:
>
>>> The device core will handle three states for you: "default", "sleep", "idle".
>>
>> Except it will handle only one state unless "CONFIG_PM" is defined,
>> right?  In other words "sleep" and "idle" totally don't exist in the
>> "!CONFIG_PM" case.
>
> Yes. Because the intent of these settings is usually to save power.
> So by disabling the PM config, you can test if the system works
> without PM. Even hairy stuff like power-related pin control. It has
> this nice orthogonal debug feature to it...
>
>> Normally it should be considered "safe" (though high power)
>> to disable CONFIG_PM, right?
>
> Yeah. If your usecase makes it unsafe to have just "default",
> you should not rely on these state names but invent new ones.

I thought about it a bit more and I decided that a new state made the
most sense.  I put another RFC up there at
<https://patchwork.kernel.org/patch/5049041/>.  Feel free to have a
look at it.

-Doug
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