linux-kernel - Re: [PATCH v10 2/2] Add PWM fan controller driver for LGM SoC

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Message-ID: <20200824081715.GA1891694@smile.fi.intel.com>
Date:   Mon, 24 Aug 2020 11:17:15 +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 v10 2/2] Add PWM fan controller driver for LGM SoC

On Mon, Aug 24, 2020 at 11:36:37AM +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.

...

> +	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_probe(dev, ret, "failed to init register map\n");
> +		return ret;
> +	}
> +
> +	pc->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(pc->clk)) {
> +		ret = PTR_ERR(pc->clk);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err_probe(dev, ret, "failed to get clock\n");
> +		return ret;
> +	}
> +
> +	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_probe(dev, ret, "failed to get reset control\n");
> +		return ret;
> +	}
> +
> +	ret = reset_control_deassert(pc->rst);
> +	if (ret) {
> +		if (ret != -EPROBE_DEFER)
> +			dev_err_probe(dev, ret, "cannot deassert reset control\n");
> +		return ret;
> +	}

Please, spend a bit of time to understand the changes you are doing. There are
already few examples how to use dev_err_probe() properly.

> +	ret = clk_prepare_enable(pc->clk);
> +	if (ret) {
> +		dev_err(dev, "failed to enable clock\n");
> +		return ret;
> +	}
> +
> +	ret = devm_add_action_or_reset(dev, lgm_pwm_action, pc);
> +	if (ret)
> +		return ret;

You have also ordering issues here.

So, what I can see about implementation is that


	static void ..._clk_disable(void *data)
	{
		clk_disable_unprepare(data);
	}

	static int ..._clk_enable(...)
	{
		int ret;

		ret = clk_preare_enable(...);
		if (ret)
			return ret;
		return devm_add_action_or_reset(..., ..._clk_disable);
	}


Similar for reset control.

Then in the ->probe() something like this:

	ret = devm_reset_control_get...;
	if (ret)
		return ret;

	ret = ..._reset_deassert(...);
	if (ret)
		return ret;

followed by similar section for the clock.

-- 
With Best Regards,
Andy Shevchenko