linux-kernel - Re: [PATCH v1 1/1] drivers/hwmon/pmbus: Add mutex to regulator ops

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Date:   Sat, 26 Feb 2022 23:42:21 +0000
From:   Zev Weiss <zweiss@...inix.com>
To:     Marcello Sylvester Bauer <sylv@...v.io>
CC:     Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        Patrick Rudolph <patrick.rudolph@...ements.com>
Subject: Re: [PATCH v1 1/1] drivers/hwmon/pmbus: Add mutex to regulator ops

On Fri, Feb 25, 2022 at 08:06:09AM PST, Marcello Sylvester Bauer wrote:
>From: Patrick Rudolph <patrick.rudolph@...ements.com>
>
>On PMBUS devices with multiple pages, the regulator ops need to be
>protected with the update mutex. This prevents accidentally changing
>the page in a separate thread while operating on the PMBUS_OPERATION
>register.
>
>Tested on Infineon xdpe11280 while a separate thread polls for sensor
>data.
>
>Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
>Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
>---
> drivers/hwmon/pmbus/pmbus_core.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
>index 776ee2237be2..f79930162256 100644
>--- a/drivers/hwmon/pmbus/pmbus_core.c
>+++ b/drivers/hwmon/pmbus/pmbus_core.c
>@@ -2386,10 +2386,14 @@ static int pmbus_regulator_is_enabled(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 ret;
>
>+	mutex_lock(&data->update_lock);
> 	ret = pmbus_read_byte_data(client, page, PMBUS_OPERATION);
>+	mutex_unlock(&data->update_lock);
>+
> 	if (ret < 0)
> 		return ret;
>
>@@ -2400,11 +2404,17 @@ static int _pmbus_regulator_on_off(struct regulator_dev *rdev, bool enable)
> {
> 	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 ret;
>
>-	return pmbus_update_byte_data(client, page, PMBUS_OPERATION,
>-				      PB_OPERATION_CONTROL_ON,
>-				      enable ? PB_OPERATION_CONTROL_ON : 0);
>+	mutex_lock(&data->update_lock);
>+	ret = pmbus_update_byte_data(client, page, PMBUS_OPERATION,
>+				     PB_OPERATION_CONTROL_ON,
>+				     enable ? PB_OPERATION_CONTROL_ON : 0);
>+	mutex_unlock(&data->update_lock);
>+
>+	return ret;
> }
>
> static int pmbus_regulator_enable(struct regulator_dev *rdev)
>-- 
>2.35.1
>
>

Looks like this doesn't cover pmbus_regulator_get_error_flags(), which
was added recently -- perhaps rebase onto hwmon-next?


Zev