quoted

This all won't have any effect since you never call i2c_recover_bus
which calls back into i2c_bus_recovery_info callbacks.

Ah, I thought there would be some use of this in the core or in client
drivers, or some ioctl interface. Would there be any outside users of these
callbacks in the future?

No. i2c_recover_bus() is only to recover from stalled SDA and the only
place where this can be detected is inside the I2C master driver. It is
not an event which can be controlled by a user.