linux-kernel - Re: [PATCH] pwm: lpc32xx

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Message-ID: <20121105210317.GA9930@avionic-0098.mockup.avionic-design.de>
Date:	Mon, 5 Nov 2012 22:03:17 +0100
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Alban Bedel <alban.bedel@...onic-design.de>
Cc:	linux-kernel@...r.kernel.org, Roland Stigge <stigge@...com.de>,
	Alexandre Pereira da Silva <aletes.xgr@...il.com>
Subject: Re: [PATCH] pwm: lpc32xx - Fix the PWM polarity

Cc'ing Roland and Alexandre. What do you guys think?

On Mon, Nov 05, 2012 at 05:48:45PM +0100, Alban Bedel wrote:
> Signed-off-by: Alban Bedel <alban.bedel@...onic-design.de>
> ---
>  drivers/pwm/pwm-lpc32xx.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-lpc32xx.c b/drivers/pwm/pwm-lpc32xx.c
> index adb87f0..a2704b8 100644
> --- a/drivers/pwm/pwm-lpc32xx.c
> +++ b/drivers/pwm/pwm-lpc32xx.c
> @@ -51,7 +51,11 @@ static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  
>  	c = 256 * duty_ns;
>  	do_div(c, period_ns);
> -	duty_cycles = c;
> +	if (c > 255)
> +		c = 255;
> +	if (c < 1)
> +		c = 1;
> +	duty_cycles = 256 - c;
>  
>  	writel(PWM_ENABLE | PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles),
>  		lpc32xx->base + (pwm->hwpwm << 2));

Shouldn't duty_cycles rather be 255 - c, such that it can still be 0?

Thierry

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