linux-kernel - Re: [PATCH] hwmon: pwm-fan: switch to new atomic PWM API

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Message-ID: <6c741041-faf4-6951-5f2d-9f7b9c54c9ca@roeck-us.net>
Date:   Mon, 24 Apr 2017 06:26:12 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jean Delvare <jdelvare@...e.com>,
        Kamil Debski <kamil@...as.org>
Cc:     Tomasz Figa <tomasz.figa@...il.com>, linux-pwm@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH] hwmon: pwm-fan: switch to new atomic PWM API

On 04/24/2017 06:13 AM, Bartlomiej Zolnierkiewicz wrote:
> Switch pwm-fan driver to new atomic PWM API.
>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> ---
> Depends on "[PATCH v2 0/3] pwm: pwm-samsung: fix suspend/resume support"
> patchset (https://www.spinics.net/lists/kernel/msg2495209.html).
>

Why would this driver, which does not depend on any Samsung code,
depend on a Samsung specific fix ?

Was this tested with hardware ?

Thanks,
Guenter

>  drivers/hwmon/pwm-fan.c | 68 +++++++++++++++++++------------------------------
>  1 file changed, 26 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 9dc40f3..4ac7700 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -40,31 +40,22 @@ struct pwm_fan_ctx {
>
>  static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
>  {
> -	struct pwm_args pargs;
> -	unsigned long duty;
> +	unsigned long period;
>  	int ret = 0;
> -
> -	pwm_get_args(ctx->pwm, &pargs);
> +	struct pwm_state state = { };
>
>  	mutex_lock(&ctx->lock);
>  	if (ctx->pwm_value == pwm)
>  		goto exit_set_pwm_err;
>
> -	duty = DIV_ROUND_UP(pwm * (pargs.period - 1), MAX_PWM);
> -	ret = pwm_config(ctx->pwm, duty, pargs.period);
> -	if (ret)
> -		goto exit_set_pwm_err;
> -
> -	if (pwm == 0)
> -		pwm_disable(ctx->pwm);
> +	pwm_init_state(ctx->pwm, &state);
> +	period = ctx->pwm->args.period;
> +	state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
> +	state.enabled = pwm ? true : false;
>
> -	if (ctx->pwm_value == 0) {
> -		ret = pwm_enable(ctx->pwm);
> -		if (ret)
> -			goto exit_set_pwm_err;
> -	}
> -
> -	ctx->pwm_value = pwm;
> +	ret = pwm_apply_state(ctx->pwm, &state);
> +	if (!ret)
> +		ctx->pwm_value = pwm;
>  exit_set_pwm_err:
>  	mutex_unlock(&ctx->lock);
>  	return ret;
> @@ -218,10 +209,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  {
>  	struct thermal_cooling_device *cdev;
>  	struct pwm_fan_ctx *ctx;
> -	struct pwm_args pargs;
>  	struct device *hwmon;
> -	int duty_cycle;
>  	int ret;
> +	struct pwm_state state = { };
>
>  	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
>  	if (!ctx)
> @@ -237,28 +227,16 @@ static int pwm_fan_probe(struct platform_device *pdev)
>
>  	platform_set_drvdata(pdev, ctx);
>
> -	/*
> -	 * FIXME: pwm_apply_args() should be removed when switching to the
> -	 * atomic PWM API.
> -	 */
> -	pwm_apply_args(ctx->pwm);
> -
> -	/* Set duty cycle to maximum allowed */
> -	pwm_get_args(ctx->pwm, &pargs);
> -
> -	duty_cycle = pargs.period - 1;
>  	ctx->pwm_value = MAX_PWM;
>
> -	ret = pwm_config(ctx->pwm, duty_cycle, pargs.period);
> -	if (ret) {
> -		dev_err(&pdev->dev, "Failed to configure PWM\n");
> -		return ret;
> -	}
> +	/* Set duty cycle to maximum allowed and enable PWM output */
> +	pwm_init_state(ctx->pwm, &state);
> +	state.duty_cycle = ctx->pwm->args.period - 1;
> +	state.enabled = true;
>
> -	/* Enbale PWM output */
> -	ret = pwm_enable(ctx->pwm);
> +	ret = pwm_apply_state(ctx->pwm, &state);
>  	if (ret) {
> -		dev_err(&pdev->dev, "Failed to enable PWM\n");
> +		dev_err(&pdev->dev, "Failed to configure PWM\n");
>  		return ret;
>  	}
>
> @@ -266,8 +244,8 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  						       ctx, pwm_fan_groups);
>  	if (IS_ERR(hwmon)) {
>  		dev_err(&pdev->dev, "Failed to register hwmon device\n");
> -		pwm_disable(ctx->pwm);
> -		return PTR_ERR(hwmon);
> +		ret = PTR_ERR(hwmon);
> +		goto err_pwm_disable;
>  	}
>
>  	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
> @@ -282,14 +260,20 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  		if (IS_ERR(cdev)) {
>  			dev_err(&pdev->dev,
>  				"Failed to register pwm-fan as cooling device");
> -			pwm_disable(ctx->pwm);
> -			return PTR_ERR(cdev);
> +			ret = PTR_ERR(cdev);
> +			goto err_pwm_disable;
>  		}
>  		ctx->cdev = cdev;
>  		thermal_cdev_update(cdev);
>  	}
>
>  	return 0;
> +
> +err_pwm_disable:
> +	state.enabled = false;
> +	pwm_apply_state(ctx->pwm, &state);
> +
> +	return ret;
>  }
>
>  static int pwm_fan_remove(struct platform_device *pdev)
>