linux-kernel - Re: [PATCH v8 2/2] Add PWM fan controller driver for LGM SoC

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Date:   Thu, 20 Aug 2020 13:52:55 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Rahul Tanwar <rahul.tanwar@...ux.intel.com>
Cc:     u.kleine-koenig@...gutronix.de, linux-pwm@...r.kernel.org,
        lee.jones@...aro.org, thierry.reding@...il.com,
        p.zabel@...gutronix.de, robh+dt@...nel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        songjun.Wu@...el.com, cheol.yong.kim@...el.com,
        qi-ming.wu@...el.com, rahul.tanwar.linux@...il.com,
        rtanwar@...linear.com
Subject: Re: [PATCH v8 2/2] Add PWM fan controller driver for LGM SoC

On Thu, Aug 20, 2020 at 12:50:46PM +0800, Rahul Tanwar wrote:
> Intel Lightning Mountain(LGM) SoC contains a PWM fan controller.
> This PWM controller does not have any other consumer, it is a
> dedicated PWM controller for fan attached to the system. Add
> driver for this PWM fan controller.

...

> +config PWM_INTEL_LGM
> +	tristate "Intel LGM PWM support"

> +	depends on OF && HAS_IOMEM
> +	depends on X86 || COMPILE_TEST

For better test coverage you may rewrite this

	depends on HAS_IOMEM
	depends on (OF && X86) || COMPILE_TEST

> +	select REGMAP_MMIO
> +	help
> +	  Generic PWM fan controller driver for LGM SoC.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-intel-lgm.

...

> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/module.h>

> +#include <linux/of_device.h>

This should be mod_devicetable.h.

> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>

...

> +#define LGM_PWM_PERIOD_2WIRE_NSECS	40000000

NSECS -> NS
40000000 -> (40 * NSEC_PER_MSEC)

...

> +	if (state->polarity != PWM_POLARITY_NORMAL ||
> +	    state->period < pc->period)

It can be one line.

> +		return -EINVAL;

...

> +	if (!state->enabled) {

> +		ret = lgm_pwm_enable(chip, 0);
> +		return ret;

What is the point?

> +	}

...

> +	ret = lgm_pwm_enable(chip, 1);
> +
> +	return ret;

Ditto.

...

> +	state->duty_cycle = DIV_ROUND_UP(duty * pc->period,
> +					 LGM_PWM_MAX_DUTY_CYCLE);

One line?

...

> +	struct lgm_pwm_chip *pc;
> +	struct device *dev = &pdev->dev;

Use reversed xmas tree order.

> +	void __iomem *io_base;
> +	int ret;

...

> +	pc->regmap = devm_regmap_init_mmio(dev, io_base, &lgm_pwm_regmap_config);
> +	if (IS_ERR(pc->regmap)) {

> +		ret = PTR_ERR(pc->regmap);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "failed to init register map: %pe\n",
> +				pc->regmap);
> +		return ret;

dev_err_probe()

> +	}

...

> +	pc->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(pc->clk)) {
> +		ret = PTR_ERR(pc->clk);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "failed to get clock: %pe\n", pc->clk);
> +		return ret;

Ditto.

> +	}
> +
> +	pc->rst = devm_reset_control_get_exclusive(dev, NULL);
> +	if (IS_ERR(pc->rst)) {
> +		ret = PTR_ERR(pc->rst);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "failed to get reset control: %pe\n",
> +				pc->rst);
> +		return ret;

Ditto.

> +	}
> +
> +	ret = reset_control_deassert(pc->rst);
> +	if (ret) {
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "cannot deassert reset control: %pe\n",
> +				ERR_PTR(ret));
> +		return ret;

Ditto.

> +	}

...

> +	ret = clk_prepare_enable(pc->clk);

Wrap it with devm_add_action_or_reset(). Same for reset_control_deassert().
You probably can even put them under one function.

> +	if (ret) {
> +		dev_err(dev, "failed to enable clock\n");
> +		reset_control_assert(pc->rst);
> +		return ret;
> +	}

...

> +	ret = pwmchip_add(&pc->chip);

> +	if (ret < 0) {

Does ' < 0' have any meaning?

> +		dev_err(dev, "failed to add PWM chip: %pe\n", ERR_PTR(ret));
> +		clk_disable_unprepare(pc->clk);
> +		reset_control_assert(pc->rst);
> +		return ret;
> +	}

...

> +	ret = pwmchip_remove(&pc->chip);
> +	if (ret < 0)

Ditto.

> +		return ret;

-- 
With Best Regards,
Andy Shevchenko