linux-kernel - Re: [RESEND][PATCH RFT 1/2] pwm: lpc32xx: Properly set PWM_ENABLE bit in lpc32xx_pwm

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Message-ID: <51764B80.80200@antcom.de>
Date:	Tue, 23 Apr 2013 10:51:12 +0200
From:	Roland Stigge <stigge@...com.de>
To:	Axel Lin <axel.lin@...ics.com>
CC:	Thierry Reding <thierry.reding@...onic-design.de>,
	Alexandre Pereira da Silva <aletes.xgr@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RESEND][PATCH RFT 1/2] pwm: lpc32xx: Properly set PWM_ENABLE
 bit in lpc32xx_pwm_[enable|disable]

On 04/23/2013 08:01 AM, Axel Lin wrote:
> According to the LPC32x0 User Manual [1]:
> 
> For both PWM1 and PWM2 Control Registers:
> BIT 31:
> This bit gates the PWM_CLK signal and enables the external output pin
> to the PWM_PIN_STATE logical level.
> 
> 0 = PWM disabled. (Default)
> 1 = PWM enabled
> 
> So in lpc32xx_pwm_enable(), we should set PWM_ENABLE bit.
> In lpc32xx_pwm_disable(), we should just clear PWM_ENABLE bit rather than
> write 0 to the register which will also clear PWMx_RELOADV and PWMx_DUTY bits.
> 
> [1] http://www.nxp.com/documents/user_manual/UM10326.pdf
> 
> Signed-off-by: Axel Lin <axel.lin@...ics.com>

Tested-by: Roland Stigge <stigge@...com.de>

> ---
> Hi,
> I don't have this hardware handy so I'd appreciate if someone can test this
> patch serial.
> 
> This patch serial was sent on https://lkml.org/lkml/2013/3/30/104
> Seems no feedback so far.
> So I just try again, maybe someone can help testing it.
> Thanks,
> Axel
> 
>  drivers/pwm/pwm-lpc32xx.c |   18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-lpc32xx.c b/drivers/pwm/pwm-lpc32xx.c
> index b3f0d0d..1a5075e 100644
> --- a/drivers/pwm/pwm-lpc32xx.c
> +++ b/drivers/pwm/pwm-lpc32xx.c
> @@ -77,15 +77,29 @@ static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>  {
>  	struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
> +	u32 val;
> +	int ret;
> +
> +	ret = clk_enable(lpc32xx->clk);
> +	if (ret)
> +		return ret;
>  
> -	return clk_enable(lpc32xx->clk);
> +	val = readl(lpc32xx->base + (pwm->hwpwm << 2));
> +	val |= PWM_ENABLE;
> +	writel(val, lpc32xx->base + (pwm->hwpwm << 2));
> +
> +	return 0;
>  }
>  
>  static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  {
>  	struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
> +	u32 val;
> +
> +	val = readl(lpc32xx->base + (pwm->hwpwm << 2));
> +	val &= ~PWM_ENABLE;
> +	writel(val, lpc32xx->base + (pwm->hwpwm << 2));
>  
> -	writel(0, lpc32xx->base + (pwm->hwpwm << 2));
>  	clk_disable(lpc32xx->clk);
>  }
>  

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