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

[Andy Shevchenko]

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