linux-kernel - Re: [PATCH v4 RESEND] pwm: atmel: add Timer Counter Block PWM driver

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Message-ID: <20130108131548.GA28676@avionic-0098.adnet.avionic-design.de>
Date:	Tue, 8 Jan 2013 14:15:48 +0100
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Boris BREZILLON <linux-arm@...rkiz.com>
Cc:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Andrew Victor <linux@...im.org.za>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org,
	Haavard Skinnemoen <hskinnemoen@...il.com>,
	Hans-Christian Egtvedt <egtvedt@...fundet.no>
Subject: Re: [PATCH v4 RESEND] pwm: atmel: add Timer Counter Block PWM driver

On Tue, Jan 08, 2013 at 01:43:56PM +0100, Boris BREZILLON wrote:
> On 08/01/2013 08:10, Thierry Reding wrote:
> > On Thu, Dec 20, 2012 at 10:12:56AM +0100, Boris BREZILLON wrote:
[...]
> >> +static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> >> +{
> > [...]
> >> +	/* If duty is 0 reverse polarity */
> >> +	if (tcbpwm->duty == 0)
> >> +		polarity = !polarity;
> > 
> > Rather than commenting on what the code does, this should say why it
> > does so.
> > 
> 
> Is this an acceptable explanation ?
> 
> 	/*
> 	 * If duty is 0 the timer will be stopped and we have to
> 	 * configure the output correctly on software trigger:
> 	 *  - set output to high if PWM_POLARITY_INVERSED
> 	 *  - set output to low if PWM_POLARITY_NORMAL
> 	 *
> 	 * This is why we're reverting polarity in this case.
> 	 */

Yes, that should work.

Thierry

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