linux-kernel - Re: [PATCH 3/3] pwm: pxa: Remove clk_enabled field from struct pxa_pwm

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Message-ID: <CAMPhdO8XqEHnmTLY9u8H+E4dQ5xvPFG4DrBFefGhXA-wYSOT1Q@mail.gmail.com>
Date:	Mon, 1 Apr 2013 15:35:17 +0800
From:	Eric Miao <eric.y.miao@...il.com>
To:	Axel Lin <axel.lin@...ics.com>
Cc:	Thierry Reding <thierry.reding@...onic-design.de>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] pwm: pxa: Remove clk_enabled field from struct pxa_pwm_chip

On Mon, Apr 1, 2013 at 3:32 PM, Axel Lin <axel.lin@...ics.com> wrote:
> 2013/4/1 Eric Miao <eric.y.miao@...il.com>:
>> On Sun, Mar 31, 2013 at 11:04 PM, Axel Lin <axel.lin@...ics.com> wrote:
>>> clk_enable/clk_disable maintain an enable_count, clk_prepare and clk_unprepare
>>> also maintain a prepare_count. These APIs will do prepare/enable when the first
>>> user calling these APIs, and do disable/unprepare when the corresponding counter
>>> reach 0. Thus We don't need to maintain a clk_enabled counter here.
>>
>> The original intention is to keep a paired clk enable counter no matter
>> how the user calls pwm_enable()/pwm_disable() in pair or not, if that's
>> no longer the case.
>
> We don't need to worry that case:
> In pwm core, both pwm_enable() and pwm_disable() will always check
> PWMF_ENABLED flag.

That's good then, this part of the code was dated before the pwm core,
looks like this has been carefully handled. Have my ack on this one then:

Acked-by: Eric Miao <eric.y.miao@...il.com>

>
>
> /**
>  * pwm_enable() - start a PWM output toggling
>  * @pwm: PWM device
>  */
> int pwm_enable(struct pwm_device *pwm)
> {
>         if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
>                 return pwm->chip->ops->enable(pwm->chip, pwm);
>
>         return pwm ? 0 : -EINVAL;
> }
> EXPORT_SYMBOL_GPL(pwm_enable);
>
> /**
>  * pwm_disable() - stop a PWM output toggling
>  * @pwm: PWM device
>  */
> void pwm_disable(struct pwm_device *pwm)
> {
>         if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
>                 pwm->chip->ops->disable(pwm->chip, pwm);
> }
> EXPORT_SYMBOL_GPL(pwm_disable);
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