From: Adam Wujek dev_public@wujek.eu
commit 75d2b2b06bd8407d03a3f126bc8b95eb356906c7 upstream.
Explicitly disable PEC when the client does not support it. The problematic scenario is the following. A device with enabled PEC support is up and running and a kernel driver is loaded. Then the driver is unloaded (or device unbound), the HW device is reconfigured externally (e.g. by i2cset) to advertise itself as not supporting PEC. Without a new code, at the second load of the driver (or bind) the "flags" variable is not updated to avoid PEC usage. As a consequence the further communication with the device is done with the PEC enabled, which is wrong and may fail.
The implementation first disable the I2C_CLIENT_PEC flag, then the old code enable it if needed.
Fixes: 4e5418f787ec ("hwmon: (pmbus_core) Check adapter PEC support") Signed-off-by: Adam Wujek dev_public@wujek.eu Link: https://lore.kernel.org/r/20220420145059.431061-1-dev_public@wujek.eu Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/hwmon/pmbus/pmbus_core.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/hwmon/pmbus/pmbus_core.c +++ b/drivers/hwmon/pmbus/pmbus_core.c @@ -2326,6 +2326,9 @@ static int pmbus_init_common(struct i2c_ data->has_status_word = true; }
+ /* Make sure PEC is disabled, will be enabled later if needed */ + client->flags &= ~I2C_CLIENT_PEC; + /* Enable PEC if the controller and bus supports it */ if (!(data->flags & PMBUS_NO_CAPABILITY)) { ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);