linux-kernel - Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support

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Message-ID: <CAKohpomectx_7Ox5os-MEA7iGsLQbDMQ_7ryuFyD437uf_Dmbg@mail.gmail.com>
Date:	Wed, 24 Oct 2012 12:07:19 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Thierry Reding <thierry.reding@...onic-design.de>
Cc:	Shiraz Hashim <shiraz.hashim@...com>, linux-kernel@...r.kernel.org,
	spear-devel@...t.st.com
Subject: Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support

On 24 October 2012 11:21, Thierry Reding
<thierry.reding@...onic-design.de> wrote:
> On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
>> +     ret = pwmchip_add(&pc->chip);
>> +     if (ret < 0) {
>> +             dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
>> +             return ret;
>> +     }
>> +
>> +     ret = clk_prepare_enable(pc->clk);
>> +     if (ret < 0)
>> +             return pwmchip_remove(&pc->chip);
>
> I think in order to fix the potential race condition that Viresh
> mentioned we should move the clk_prepare_enable() before the
> pwmchip_add(), but don't forget to disable and unprepare the clock if
> pwmchip_add() fails.
>
> Actually, can't we make it a clk_prepare() only at this point and move
> the clk_enable() and clk_disable() into the if block below? In case the
> compatible value is not "st,spear1340-pwm" we don't need the clock
> enabled.

We should. I should have given this comment earlier.

--
viresh
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