While Google's Ara Modular Phone Is Dead, Greybus Still Appears To Have A Future

Written by Michael Larabel in Hardware on 6 October 2016 at 07:46 AM EDT. 31 Comments
HARDWARE
With the Linux 4.9 staging pull request comes the addition of the Greybus subsystem. A major user of the Greybus subsystem was to be Google's Project Ara modular smartphone, but with that initiative recently being canned, it may seem like Greybus is dead but that's not actually the case.

When the Linux 4.9 staging pull request was sent in with this huge addition, some were wondering what it's purpose was if there is no real-world use. Linus Torvalds also was wondering the same thing. Greybus was key to Project Ara and is an application-level protocol for the UniPro (Unified Protocol) hardware transport.

Greg Kroah-Hartman responded to Torvalds' inquiry with justification for merging Greybus to the mainline Linux kernel:
Right now there is a phone from Motorola shipping with this code (a slightly older version, but the same tree), so even though Ara is not alive in the same form, the functionality is happening. We are working with the developers of that phone to merge the newer stuff in with their fork so they can use the upstream version in future versions of their phone product line.

Toshiba has at least one chip shipping in their catalog that needs/uses this protocol over a Unipro link, and rumor has it that there might be more in the future.

There are also other users of the greybus protocols, there is a talk next week at ELC that shows how it is being used across a network connection to control a device, and previous ELC talks have showed the protocol stack being used over USB to drive embedded Linux boards. I've also talked to some people who are starting to work to add a host controller driver to control arduinos as the greybus PHY protocols are very useful to control a serial/i2c/spio/whatever device across a random physical link, as it is a way to have a self-describing device be attached to a host without needing manual configuration.

So yes, people are using it, and there is still the chance that it will show up in a phone/laptop/tablet/whatever from Google in the future as well, the tech isn't dead, even if the original large phone project happens to be.
Interesting to hear, especially that Google may still be spinning something with it in the future. Linus subsequently pulled the staging changes with Greybus included.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

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