Since it is a workspace with 3 components:

• crate library
• ffi for the crate library
• cli utilities

It is common to either have

• The crate library as root crate, ffi and cli in crates/ as v4l2r-ffi and v4l2r-cli
• Everything in crates/ as v4l2r, v4l2r-ffi, v4l2r-cli.

Are you fine with either refactor?