Greybus Subsystem Proposed For Linux 4.9 Kernel

Greg Kroah-Hartman is looking to land the Greybus driver subsystem into the upcoming Linux 4.9 kernel subsystem. Greybus was a central piece to Google's recently cancelled Project Ara modular smartphone.

Greybus is an application-level protocol for the UniPro (Unified Protocol) hardware transport. Greybus is central to Google's Project Ara smartphone, which was announced earlier this month as being canned by Google. However, Greybus is supposed to be shipping in a Motorola phone "any-day-now", according to Greg KH.

UniPro is the protocol for inter-module communication on these modular phones while Greybus specifies the application layer / behavior of the software interacting with the different interfaces.

Many developers have been working on this Greybus subsystem for Linux for 2~3 years while he is planning to merge it for Linux 4.9. The protocol specification to Greybus is publicly available, a new version of this protocol that's already implemented by this code will be published soon, and various user-space components to Greybus are publicly available.

More details on Greybus and the Linux 4.9 kernel plans can be found via this kernel mailing list message. With Project Ara being cancelled, it will be interesting to see what happens of Greybus in the mainline Linux kernel and what other Google projects or other hardware vendors may end up utilizing Greybus.