Leave Alone IO is a feature in Lattice ispVM software which allows Lattice devices to sample the IOs and hold their values during programming. You can select Leave Alone IO in ispVM software when building a program chain (.xcf file).
The Leave Alone IO is active when the device is in TransFR mode (for certain Lattice device families) or in foreground programming mode, where the operation of the IOs is interrupted. The Leave Alone IO feature is used to keep the IO states steady during the time the device is reprogrammed. At the conclusion of the programming cycle the IOs are no longer statically held, and return to their normal operational behavior.
The Leave Alone IO is ignored by ispVM when the device is in background programming mode. During background programming, Leave Alone IO is not needed because the IOs are still working properly.