Hi Andy,

On 20/8/2020 6:52 pm, Andy Shevchenko wrote:

On Thu, Aug 20, 2020 at 12:50:46PM +0800, Rahul Tanwar wrote:

quoted

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.

...

quoted

+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

Sure, will update.

quoted

+	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.

...

quoted

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

This should be mod_devicetable.h.

Well noted.

quoted

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

...

quoted

+#define LGM_PWM_PERIOD_2WIRE_NSECS	40000000

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

Well noted.

...

quoted

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

It can be one line.

Ok.

quoted

+		return -EINVAL;

...

quoted

+	if (!state->enabled) {
+		ret = lgm_pwm_enable(chip, 0);
+		return ret;

What is the point?

I guess you mean to change it to return lgm_pwm_enable(chip, 0);
Will do, thanks.

quoted

+	}

...

quoted

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

Ditto.

...

quoted

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

One line?

Ok.

...

quoted

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

Use reversed xmas tree order.

Sure, will update.

quoted

+	void __iomem *io_base;
+	int ret;

...

quoted

+	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()

Will update. Thanks.

quoted

+	}

...

quoted

+	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.

quoted

+	}
+
+	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.

quoted

+	}
+
+	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.

quoted

+	}

...

quoted

+	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.

I did some study and research for using devm_add_action_or_reset(). But
still i have some doubts. Below steps is what i intend to do in order to
switch to using this API. Please do review and let me know it is ok and
i am not missing anything else. Thanks.

1. Call reset_control_assert()
2. Call clk_prepare_enable()
3. Call pwmchip_add()
4. Call devm_add_action_or_reset(dev, my_action, pc)
5. Remove explicit calls to unprepare/reset_control_assert from probe in
failure cases.
6. static void my_action(void *pc)
   {
      pwmchip_remove(&pc->chip);
      clk_disable_upprepare(pc->clk);
      reset_control_assert(pc->rst);
   }
7. Remove platform_driver.remove() entirely.

quoted

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

...

quoted

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

Does ' < 0' have any meaning?

I use < 0 because this API's return code is mentioned as below:
Returns: 0 on success or a negative error code on failure.
Also, all other PWM drivers check for <0 for this call.

quoted

+		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;
+	}

...

quoted

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

Ditto.

Same as above.

quoted

+		return ret;

Thanks.

Regards,
Rahul