[xx_ns]

Mesa isn't a driver. Mesa is just an abstraction on top of the software that DRIVES the hardware (a driver), which is being written from scratch. Nobody (including the Asahi developers) but you subscribes to your definition of a driver. Drivers implementing Mesa may share next to nothing in common, so no, it's not a "port".

[est31]

The ashahi driver inside Mesa builds upon Gallium3D so it does use shared components of the Mesa library stack. This is not a from scratch driver, it's one that uses the powers of the Mesa library.