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Date:   Tue, 2 Jun 2020 07:28:13 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Sandipan Patra <spatra@nvidia.com>
Cc:     treding@nvidia.com, jonathanh@nvidia.com, kamil@wypas.org,
        jdelvare@suse.com, robh+dt@kernel.org,
        u.kleine-koenig@pengutronix.de, bbasu@nvidia.com,
        bbiswas@nvidia.com, kyarlagadda@nvidia.com,
        linux-pwm@vger.kernel.org, linux-hwmon@vger.kernel.org,
        devicetree@vger.kernel.org, linux-tegra@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2 1/2] hwmon: pwm-fan: Add profile support and add
 remove module support
Message-ID: <20200602142813.GA54592@roeck-us.net>
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On Mon, Jun 01, 2020 at 11:49:13AM +0530, Sandipan Patra wrote:
> Add support for profiles mode settings.
> This allows different fan settings for trip point temp/hyst/pwm.
> Tegra194 has multiple fan-profiles support.
> 
> Signed-off-by: Sandipan Patra <spatra@nvidia.com>

The subject says "remove module support". What is this supposed to be
about ?

The code adds support for multiple cooling "profiles" but, unless I am
really missing something, no means to actually select a profile.
This adds a lot of complexity to the code with zero value.

Either case, and I may have mentioned this before, functionality like this
should really reside in the thermal core and not in individual drivers.

> ---
> 
> PATCH V2:
> 	Cleaned pwm_fan_remove support as it is not required.
> 
>  drivers/hwmon/pwm-fan.c | 92 ++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 80 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 30b7b3e..1d2a416 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -3,8 +3,10 @@
>   * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
>   *
>   * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Copyright (c) 2020, NVIDIA Corporation.
>   *
>   * Author: Kamil Debski <k.debski@samsung.com>
> + * Author: Sandipan Patra <spatra@nvidia.com>

You can not claim authorship for a driver by adding a few lines of code
to it.

>   */
>  
>  #include <linux/hwmon.h>
> @@ -21,6 +23,8 @@
>  #include <linux/timer.h>
>  
>  #define MAX_PWM 255
> +/* Based on OF max device tree node name length */
> +#define MAX_PROFILE_NAME_LENGTH	31
>  
>  struct pwm_fan_ctx {
>  	struct mutex lock;
> @@ -38,6 +42,12 @@ struct pwm_fan_ctx {
>  	unsigned int pwm_fan_state;
>  	unsigned int pwm_fan_max_state;
>  	unsigned int *pwm_fan_cooling_levels;
> +
> +	unsigned int pwm_fan_profiles;
> +	const char **fan_profile_names;
> +	unsigned int **fan_profile_cooling_levels;
> +	unsigned int fan_current_profile;
> +
>  	struct thermal_cooling_device *cdev;
>  };
>  
> @@ -227,28 +237,86 @@ static int pwm_fan_of_get_cooling_data(struct device *dev,
>  				       struct pwm_fan_ctx *ctx)
>  {
>  	struct device_node *np = dev->of_node;
> +	struct device_node *base_profile = NULL;
> +	struct device_node *profile_np = NULL;
> +	const char *default_profile = NULL;
>  	int num, i, ret;
>  
> -	if (!of_find_property(np, "cooling-levels", NULL))
> -		return 0;
> +	num = of_property_count_u32_elems(np, "cooling-levels");
> +	if (num <= 0) {
> +		base_profile = of_get_child_by_name(np, "profiles");

You can not just add new properties like this without documenting it
and getting approval by devicetree maintainers.

Guenter

> +		if (!base_profile) {
> +			dev_err(dev, "Wrong Data\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	if (base_profile) {
> +		ctx->pwm_fan_profiles =
> +			of_get_available_child_count(base_profile);
>  
> -	ret = of_property_count_u32_elems(np, "cooling-levels");
> -	if (ret <= 0) {
> -		dev_err(dev, "Wrong data!\n");
> -		return ret ? : -EINVAL;
> +		if (ctx->pwm_fan_profiles <= 0) {
> +			dev_err(dev, "Profiles used but not defined\n");
> +			return -EINVAL;
> +		}
> +
> +		ctx->fan_profile_names = devm_kzalloc(dev,
> +			sizeof(const char *) * ctx->pwm_fan_profiles,
> +							GFP_KERNEL);
> +		ctx->fan_profile_cooling_levels = devm_kzalloc(dev,
> +			sizeof(int *) * ctx->pwm_fan_profiles,
> +							GFP_KERNEL);
> +
> +		if (!ctx->fan_profile_names
> +				|| !ctx->fan_profile_cooling_levels)
> +			return -ENOMEM;
> +
> +		ctx->fan_current_profile = 0;
> +		i = 0;
> +		for_each_available_child_of_node(base_profile, profile_np) {
> +			num = of_property_count_u32_elems(profile_np,
> +							"cooling-levels");
> +			if (num <= 0) {
> +				dev_err(dev, "No data in cooling-levels inside profile node!\n");
> +				return -EINVAL;
> +			}
> +
> +			of_property_read_string(profile_np, "name",
> +						&ctx->fan_profile_names[i]);
> +			if (default_profile &&
> +				!strncmp(default_profile,
> +				ctx->fan_profile_names[i],
> +				MAX_PROFILE_NAME_LENGTH))
> +				ctx->fan_current_profile = i;
> +
> +			ctx->fan_profile_cooling_levels[i] =
> +				devm_kzalloc(dev, sizeof(int) * num,
> +							GFP_KERNEL);
> +			if (!ctx->fan_profile_cooling_levels[i])
> +				return -ENOMEM;
> +
> +			of_property_read_u32_array(profile_np, "cooling-levels",
> +				ctx->fan_profile_cooling_levels[i], num);
> +			i++;
> +		}
>  	}
>  
> -	num = ret;
>  	ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
>  						   GFP_KERNEL);
>  	if (!ctx->pwm_fan_cooling_levels)
>  		return -ENOMEM;
>  
> -	ret = of_property_read_u32_array(np, "cooling-levels",
> -					 ctx->pwm_fan_cooling_levels, num);
> -	if (ret) {
> -		dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
> -		return ret;
> +	if (base_profile) {
> +		memcpy(ctx->pwm_fan_cooling_levels,
> +		  ctx->fan_profile_cooling_levels[ctx->fan_current_profile],
> +						num);
> +	} else {
> +		ret = of_property_read_u32_array(np, "cooling-levels",
> +				ctx->pwm_fan_cooling_levels, num);
> +		if (ret) {
> +			dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
> +			return -EINVAL;
> +		}
>  	}
>  
>  	for (i = 0; i < num; i++) {