Thank you for you thorough review, it sums up nicely the patchset.
Question: *_are we comfortable with preserving app compatibility, butThis question is really critical.
If we have to support all API layers from 1.0: app, driver's interface,
low level kernel API - device for instance - etc.... things are going to
be much harder when introducing changes.
Another question: I had asked you to mark gpio_set_callback() withAs far as I remember (CI does not have the logs, it drops them after
some time), it was failing due to gpio_api_compat.c which was
implementing the deprecated function, using the deprecated gpio_callback_t
That said, I could disable by default such compat layer, and set the
deprecated in a last patch yes. Should fix this issue.