ret = iio_channel_attr_write(phy_chn_rx, "rf_port_select", rxcfg.rfport);
I get a -22
Other settings for the rx channel work
phy_chn_rx = iio_device_find_channel(phydev, "voltage0", false );
gives the channel for rx. This one works.
Additionally is of value to assign settings to altvoltage0 or altvoltage1 for the PLUTO?
It seems they are not available ...