linux-kernel - Re: [PATCH v3 4/4] pwm: imx27: return error, if clean PWM setup fails

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Date:   Wed, 6 Sep 2023 17:44:06 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Leif Middelschulte <leif.middelschulte@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-pwm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/4] pwm: imx27: return error, if clean PWM setup fails

On Tue, Aug 15, 2023 at 12:43:32PM +0200, Leif Middelschulte wrote:
> Instead of issuing a warning, return an error (as adviced[0]), if the
> FIFO cannot be cleanly set up.
> 
> [0] https://lore.kernel.org/lkml/20230310174517.rb7xxrougkse2lrc@pengutronix.de/T/#ec9560c1f613d9c0d7b77d72ad9051768812f80db
> 
> Signed-off-by: Leif Middelschulte <Leif.Middelschulte@...il.com>
> ---
>  drivers/pwm/pwm-imx27.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
> index 9673e809d212..5fd6d34a7722 100644
> --- a/drivers/pwm/pwm-imx27.c
> +++ b/drivers/pwm/pwm-imx27.c
> @@ -133,14 +133,15 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip,
>  		sr = readl(imx->mmio_base + MX3_PWMSR);
>  		fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);
>  		if (fifoav == MX3_PWMSR_FIFOAV_EMPTY)
> -			return;
> +			return 0;
>  		/* if the FIFO value does not decrease, there is another problem */
>  		if (previous_fifoav == fifoav)
>  			break;
>  		previous_fifoav = fifoav;
>  		msleep(period_ms);
>  	}
> -	dev_warn(dev, "FIFO has been refilled concurrently\n");
> +
> +	return -EAGAIN;
>  }
>  
>  static int pwm_imx27_get_state(struct pwm_chip *chip,
> @@ -208,7 +209,9 @@ static int pwm_imx27_get_state(struct pwm_chip *chip,
>  		 * been supplied and a period expired between the call of the wait
>  		 * function and the subsequent readl.
>  		 */
> -		pwm_imx27_wait_fifo_empty(chip, pwm);
> +		ret = pwm_imx27_wait_fifo_empty(chip, pwm);
> +		if (ret)
> +			return ret;
>  		val = readl(imx->mmio_base + MX3_PWMSAR);
>  	} else {
>  		val = imx->duty_cycle;

I'd squash this into the patch introducing pwm_imx27_wait_fifo_empty,
too.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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