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

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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@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Signed-off-by: Marcello Sylvester Bauer <sylv@xxxxxxx>
---
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?


This is a bug fix which needs to be applied to stable releases, or am I
missing something ?

Guenter



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