On Fri, Jun 04, 2021 at 02:16:02PM +0200, Robert Marko wrote: [ ... ] > > > > > +} > > > + > > > +static int dps920ab_write_word_data(struct i2c_client *client, int page, int reg, > > > + u16 word) > > > +{ > > > + int ret; > > > + > > > + /* > > > + * This masks commands which are not supported. > > > + * PSU only has one R/W register and that is > > > + * for the fan. > > > + */ > > > + switch (reg) { > > > + case PMBUS_FAN_COMMAND_1: > > > + break; > > > + default: > > > + ret = -ENODATA; > > > + } > > > + > > > > Does this work ? It is the wrong error message for a failed write; > > it should probably return -EACCES. > > It appears to work fine, I was looking at other drivers, and all of them > use -ENODATA for unsupported word registers. No. They return -ENODATA to tell the PMBus core to use standard PMBus access functions, ie to handle the access in the core. Please see _pmbus_write_word_data(). Guenter