linux-kernel - Re: [PATCH v2] hwmon: pm_bus: core: Implement regulator get

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Date:   Fri, 18 Nov 2022 04:10:49 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Naresh Solanki <naresh.solanki@...ements.com>
Cc:     linux-hwmon@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] hwmon: pm_bus: core: Implement regulator get_status

On Fri, Nov 18, 2022 at 09:46:36AM +0100, Naresh Solanki wrote:
> From: Patrick Rudolph <patrick.rudolph@...ements.com>
> 
> Add get_status for pmbus_regulator_ops.
> 
> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> ---

Please provide change logs.

>  drivers/hwmon/pmbus/pmbus_core.c | 72 ++++++++++++++++++++++++++++++++
>  1 file changed, 72 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index 7ec04934747e..5dde345c7679 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -2851,6 +2851,77 @@ static int pmbus_regulator_get_error_flags(struct regulator_dev *rdev, unsigned
>  	return 0;
>  }
>  
> +static int pmbus_regulator_get_status(struct regulator_dev *rdev)
> +{
> +	struct device *dev = rdev_get_dev(rdev);
> +	struct i2c_client *client = to_i2c_client(dev->parent);
> +	struct pmbus_data *data = i2c_get_clientdata(client);
> +	u8 page = rdev_get_id(rdev);
> +	int status, status2;
> +
> +	mutex_lock(&data->update_lock);
> +	status = pmbus_get_status(client, page, PMBUS_STATUS_WORD);
> +	mutex_unlock(&data->update_lock);

I do not see the point of this lock here and elsewhere in this function.
If you want to ensure that the status is consistent, you would need to
hold the lock over the entire function, not repeatedly acquire and release
it. Even then there would be no guarantee that the status is consistent
because it can change anytime on the chip side.

> +	if (status < 0)
> +		return status;
> +
> +	if (status & (PB_STATUS_VIN_UV | PB_STATUS_IOUT_OC | PB_STATUS_VOUT_OV |
> +	    PB_STATUS_UNKNOWN))

Please align continuation lines with the matching '('.

> +		return REGULATOR_STATUS_ERROR;
> +
> +	if (status & (PB_STATUS_OFF | PB_STATUS_POWER_GOOD_N))
> +		return REGULATOR_STATUS_OFF;
> +
> +	if (status & PB_STATUS_VOUT &&
> +	    data->info->func[page] & PMBUS_HAVE_STATUS_VOUT) {
> +		mutex_lock(&data->update_lock);
> +		status2 = _pmbus_read_byte_data(client, page,
> +					 PMBUS_STATUS_VOUT);
> +		mutex_unlock(&data->update_lock);
> +		if (status2 < 0)
> +			return status2;
> +		if (status2 & (PB_VOLTAGE_OV_FAULT | PB_VOLTAGE_UV_FAULT))
> +			return REGULATOR_STATUS_ERROR;
> +	}
> +	if (status & PB_STATUS_IOUT_POUT &&
> +	    data->info->func[page] & PMBUS_HAVE_STATUS_IOUT) {
> +		mutex_lock(&data->update_lock);
> +		status2 = _pmbus_read_byte_data(client, page,
> +						 PMBUS_STATUS_IOUT);

Ok to avoid continuation lines as long as the result has less then 100
columns.

> +		mutex_unlock(&data->update_lock);
> +		if (status2 < 0)
> +			return status2;
> +		if (status2 & (PB_POUT_OP_FAULT | PB_IOUT_UC_FAULT |
> +		    PB_IOUT_OC_LV_FAULT | PB_IOUT_OC_FAULT))
> +			return REGULATOR_STATUS_ERROR;
> +	}
> +	if (status & PB_STATUS_INPUT &&
> +	    data->info->func[page] & PMBUS_HAVE_STATUS_INPUT) {
> +		mutex_lock(&data->update_lock);
> +		status2 = _pmbus_read_byte_data(client, page,
> +						 PMBUS_STATUS_INPUT);
> +		mutex_unlock(&data->update_lock);
> +		if (status2 < 0)
> +			return status2;
> +		if (status2 & (PB_IIN_OC_FAULT | PB_VOLTAGE_OV_FAULT |
> +		    PB_VOLTAGE_UV_FAULT))
> +			return REGULATOR_STATUS_ERROR;
> +	}
> +	if (status & PB_STATUS_TEMPERATURE &&
> +	    data->info->func[page] & PMBUS_HAVE_STATUS_TEMP) {
> +		mutex_lock(&data->update_lock);
> +		status2 = _pmbus_read_byte_data(client, page,
> +						 PMBUS_STATUS_TEMPERATURE);
> +		mutex_unlock(&data->update_lock);
> +		if (status2 < 0)
> +			return status2;
> +		if (status2 & (PB_TEMP_UT_FAULT | PB_TEMP_OT_FAULT))
> +			return REGULATOR_STATUS_ERROR;
> +	}
> +
> +	return REGULATOR_STATUS_ON;
> +}
> +
>  static int pmbus_regulator_get_low_margin(struct i2c_client *client, int page)
>  {
>  	struct pmbus_data *data = i2c_get_clientdata(client);
> @@ -2991,6 +3062,7 @@ const struct regulator_ops pmbus_regulator_ops = {
>  	.disable = pmbus_regulator_disable,
>  	.is_enabled = pmbus_regulator_is_enabled,
>  	.get_error_flags = pmbus_regulator_get_error_flags,
> +	.get_status = pmbus_regulator_get_status,
>  	.get_voltage = pmbus_regulator_get_voltage,
>  	.set_voltage = pmbus_regulator_set_voltage,
>  	.list_voltage = pmbus_regulator_list_voltage,
> 
> base-commit: 27fea302952d8c90cafbdbee96bafeca03544401
> -- 
> 2.37.3
>