linux-kernel - Re: [PATCH 3/6] pwm: imx: Move PWMv2 wait for fifo slot code to a separate function

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Date:   Mon, 24 Oct 2016 17:23:49 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Lukasz Majewski <l.majewski@...ess.pl>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Stefan Agner <stefan@...er.ch>, linux-pwm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Fabio Estevam <fabio.estevam@....com>,
        Fabio Estevam <festevam@...il.com>,
        Lothar Wassmann <LW@...o-electronics.de>,
        Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>,
        kernel@...gutronix.de
Subject: Re: [PATCH 3/6] pwm: imx: Move PWMv2 wait for fifo slot code to a
 separate function

On Sun, 23 Oct 2016 23:45:43 +0200
Lukasz Majewski <l.majewski@...ess.pl> wrote:

> The code, which waits for fifo slot, has been extracted from
> imx_pwm_config_v2 function and moved to new one - imx_pwm_wait_fifo_slot().
> 
> This change reduces the overall size of imx_pwm_config_v2() and prepares
> it for atomic PWM operation.
> 
> Suggested-by: Stefan Agner <stefan@...er.ch>
> Suggested-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> Signed-off-by: Lukasz Majewski <l.majewski@...ess.pl>

Reviewed-by: Boris Brezillon <boris.brezillon@...e-electrons.com>

> ---
>  drivers/pwm/pwm-imx.c | 42 +++++++++++++++++++++++++-----------------
>  1 file changed, 25 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> index fac5c93..f3577c5 100644
> --- a/drivers/pwm/pwm-imx.c
> +++ b/drivers/pwm/pwm-imx.c
> @@ -149,18 +149,36 @@ static void imx_pwm_sw_reset(struct pwm_chip *chip)
>  		dev_warn(dev, "software reset timeout\n");
>  }
>  
> +static void imx_pwm_wait_fifo_slot(struct pwm_chip *chip,
> +				   struct pwm_device *pwm)
> +{
> +	struct imx_chip *imx = to_imx_chip(chip);
> +	struct device *dev = chip->dev;
> +	unsigned int period_ms;
> +	int fifoav;
> +	u32 sr;
> +
> +	sr = readl(imx->mmio_base + MX3_PWMSR);
> +	fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
> +	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
> +		period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
> +					 NSEC_PER_MSEC);
> +		msleep(period_ms);
> +
> +		sr = readl(imx->mmio_base + MX3_PWMSR);
> +		if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
> +			dev_warn(dev, "there is no free FIFO slot\n");
> +	}
> +}
>  
>  static int imx_pwm_config_v2(struct pwm_chip *chip,
>  		struct pwm_device *pwm, int duty_ns, int period_ns)
>  {
>  	struct imx_chip *imx = to_imx_chip(chip);
> -	struct device *dev = chip->dev;
>  	unsigned long long c;
>  	unsigned long period_cycles, duty_cycles, prescale;
> -	unsigned int period_ms;
>  	bool enable = pwm_is_enabled(pwm);
> -	int fifoav;
> -	u32 cr, sr;
> +	u32 cr;
>  
>  	/*
>  	 * i.MX PWMv2 has a 4-word sample FIFO.
> @@ -169,19 +187,9 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
>  	 * wait for a full PWM cycle to get a relinquished FIFO slot
>  	 * when the controller is enabled and the FIFO is fully loaded.
>  	 */
> -	if (enable) {
> -		sr = readl(imx->mmio_base + MX3_PWMSR);
> -		fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
> -		if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
> -			period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
> -						 NSEC_PER_MSEC);
> -			msleep(period_ms);
> -
> -			sr = readl(imx->mmio_base + MX3_PWMSR);
> -			if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
> -				dev_warn(dev, "there is no free FIFO slot\n");
> -		}
> -	} else
> +	if (enable)
> +		imx_pwm_wait_fifo_slot(chip, pwm);
> +	else
>  		imx_pwm_sw_reset(chip);
>  
>  	c = clk_get_rate(imx->clk_per);