------- Original Message ------- On Wednesday, April 20th, 2022 at 00:00, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > > On 4/19/22 13:53, Adam Wujek wrote: > > > Explicitly disable PEC when the client does not support it. > > Without the explicit disable, when the device with the PEC support is removed > > later when a device without PEC support is inserted into the same address, > > the driver uses the old value of client->flags which contains the I2C_CLIENT_PEC > > flag. As a consequence the PEC is used when it should not. > > > How can that happen ? I would assume the I2C device gets deleted and re-created > in that case, which should clear the PEC flag. > > Guenter In my case it was when I unloaded the driver for the I2C slave, changed the advertised PEC value in PMBUS_CAPABILITY register on slave. Then loaded the driver. When the switch was from disable->enable it worked as expected (this case was already covered), but when the PEC was set in the slave from enabled->disabled it was still using PEC to communicate. Adam > > > Signed-off-by: Adam Wujek dev_public@xxxxxxxx > > --- > > drivers/hwmon/pmbus/pmbus_core.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c > > index 82c3754e21e3..f8ca36759b0a 100644 > > --- a/drivers/hwmon/pmbus/pmbus_core.c > > +++ b/drivers/hwmon/pmbus/pmbus_core.c > > @@ -2014,6 +2014,8 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data, > > ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY); > > if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK)) > > client->flags |= I2C_CLIENT_PEC; > > + else > > + client->flags &= ~I2C_CLIENT_PEC; > > > > pmbus_clear_faults(client); > > > > -- > > 2.17.1
