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SubjectRe: [PATCH 2/2] hwmon: pwm-fan: Add optional regulator support
On Tue, Jan 29, 2019 at 06:07:11PM +0100, Stefan Wahren wrote:
> This adds optional regulator support to the pwm-fan driver. This is
> necessary for pwm fans which are powered by a switchable supply.
>
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
> drivers/hwmon/pwm-fan.c | 35 +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 2c94482..9e0591e 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -23,6 +23,7 @@
> #include <linux/of.h>
> #include <linux/platform_device.h>
> #include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>
> #include <linux/sysfs.h>
> #include <linux/thermal.h>
>
> @@ -31,6 +32,7 @@
> struct pwm_fan_ctx {
> struct mutex lock;
> struct pwm_device *pwm;
> + struct regulator *reg_en;
> unsigned int pwm_value;
> unsigned int pwm_fan_state;
> unsigned int pwm_fan_max_state;
> @@ -244,6 +246,23 @@ static int pwm_fan_probe(struct platform_device *pdev)
> return ret;
> }
>
> + ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
> + if (!IS_ERR(ctx->reg_en)) {

It is customary to handle the error case first.

> + ret = regulator_enable(ctx->reg_en);
> + if (ret)
> + dev_err(&pdev->dev,
> + "Failed to enable fan supply: %d\n", ret);
> + } else {
> + switch (PTR_ERR(ctx->reg_en)) {
> + case -ENODEV:
> + case -ENOSYS:

Does devm_regulator_get_optional() ever return -ENOSYS ?
I glanced through other calls to devm_regulator_get_optional(),
but I don't see that check anywhere.

> + ctx->reg_en = NULL;
> + break;
> + default:
> + return PTR_ERR(ctx->reg_en);
> + }

This is inconsistent. Provided regulators which fail to enable are
accepted, albeit with an error message, while unexpected errors from
devm_regulator_get_optional() result in a bailout. Please be consistent.

> + }
> +
> hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
> ctx, pwm_fan_groups);
> if (IS_ERR(hwmon)) {
> @@ -287,6 +306,10 @@ static int pwm_fan_remove(struct platform_device *pdev)
> thermal_cooling_device_unregister(ctx->cdev);
> if (ctx->pwm_value)
> pwm_disable(ctx->pwm);
> +
> + if (ctx->reg_en)
> + regulator_disable(ctx->reg_en);

As written, this is also called after regulator_enable() failed.
Same below.

> +
> return 0;
> }
>
> @@ -299,6 +322,12 @@ static int pwm_fan_suspend(struct device *dev)
>
> pwm_get_args(ctx->pwm, &args);
>
> + if (ctx->reg_en) {
> + ret = regulator_disable(ctx->reg_en);
> + if (ret)
> + dev_err(dev, "Failed to disable fan supply: %d\n", ret);
> + }
> +
> if (ctx->pwm_value) {
> ret = pwm_config(ctx->pwm, 0, args.period);
> if (ret < 0)
> @@ -317,6 +346,12 @@ static int pwm_fan_resume(struct device *dev)
> unsigned long duty;
> int ret;
>
> + if (ctx->reg_en) {
> + ret = regulator_enable(ctx->reg_en);
> + if (ret)
> + dev_err(dev, "Failed to enable fan supply: %d\n", ret);
> + }
> +
> if (ctx->pwm_value == 0)
> return 0;
>

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