You have two options: - either you give your users an ability to upgrade the firmware, so they can RE it, write and use an open replacement - or you don't giv

You have two options: - either you give your users an ability to upgrade the firmware, so they can RE it, write and use an open replacement - or you don't give your users an ability to upgrade, which doesn't help anyone since they can never be sure if the chip manufacturer didn't put some undocumented interface somewhere that even you weren't aware of; so now only the chip manufacturer can upgrade the firmware and the user can't Realistically, in a context of mobile phone components, there hardly such thing as "not updatable firmware". You can never be sure.