Thread (6 messages) 6 messages, 2 authors, 2020-08-24

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

From: Andy Shevchenko <hidden>
Date: 2020-08-24 08:17:23
Also in: linux-pwm, lkml

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

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