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From:   Zev Weiss <zweiss@equinix.com>
To:     Guenter Roeck <linux@roeck-us.net>
CC:     Marcello Sylvester Bauer <sylv@sylv.io>,
        Jean Delvare <jdelvare@suse.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
        Patrick Rudolph <patrick.rudolph@9elements.com>
Subject: Re: [PATCH v1 1/1] drivers/hwmon/pmbus: Add mutex to regulator ops
Thread-Topic: [PATCH v1 1/1] drivers/hwmon/pmbus: Add mutex to regulator ops
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Date:   Sat, 26 Feb 2022 23:59:46 +0000
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On Sat, Feb 26, 2022 at 03:47:41PM PST, Guenter Roeck wrote:
>On 2/26/22 15:42, Zev Weiss wrote:
>>On Fri, Feb 25, 2022 at 08:06:09AM PST, Marcello Sylvester Bauer wrote:
>>>From: Patrick Rudolph <patrick.rudolph@9elements.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@9elements.com>
>>>Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.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/pmbu=
s_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 reg=
ulator_dev *rdev)
>>>{
>>>	struct device *dev =3D rdev_get_dev(rdev);
>>>	struct i2c_client *client =3D to_i2c_client(dev->parent);
>>>+	struct pmbus_data *data =3D i2c_get_clientdata(client);
>>>	u8 page =3D rdev_get_id(rdev);
>>>	int ret;
>>>
>>>+	mutex_lock(&data->update_lock);
>>>	ret =3D 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 regula=
tor_dev *rdev, bool enable)
>>>{
>>>	struct device *dev =3D rdev_get_dev(rdev);
>>>	struct i2c_client *client =3D to_i2c_client(dev->parent);
>>>+	struct pmbus_data *data =3D i2c_get_clientdata(client);
>>>	u8 page =3D 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 =3D 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)
>>>--=20
>>>2.35.1
>>>
>>>
>>
>>Looks like this doesn't cover pmbus_regulator_get_error_flags(), which
>>was added recently -- perhaps rebase onto hwmon-next?
>>
>
>This is a bug fix which needs to be applied to stable releases, or am I
>missing something ?
>

Ah, true -- should it then be a two-patch series, with this as the first
for -stable and then a second for -next that extends it to include
pmbus_regulator_get_error_flags()?


Zev