I completely agree with this, but it's not backward compatible, that's why I used the full mask 0xff.

I don't think we have ever cared about maintaining backwards compatibility in master. Maybe I'm wrong, but otherwise we'd never be able to move forward. I can see the issue though -- a user updates from 1.16 to 1.17 and now their escs don't work. To draw a comparison, between 1.15 and 1.16 we split the RC protocols out of rc_input and into per-protocol drivers and set all protocols to default disabled. This has resulted in many users reporting "rc doesn't work". It was a necessary breaking change, but it caused users pain. For manufacturers this can be solved in the airframe file using PARAM_DEFAULTS_VER
https://docs.px4.io/main/en/dev_airframes/adding_a_new_frame.html#force-reset-of-airframe-parameters-on-update

For boards that don't have a CAN2 interface, we should add a board param default to the CAN interface it has, ie CAN1.

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