[OpenWrt-Devel] ar71xx: How to integrate UniFi AP Outdoor Plus HSR?

Stefan Rompf stefan at loplof.de
Wed May 27 16:48:21 EDT 2015

Hi Kirill,

> So I made a patch for atheros driver and it works. A signal level on
> different frequencies is more or less equal and seems adequate (about
> -30 dbm if a client within a meter from ap).

so you reverse engineered the timer values, the response format and the 's' 
command I had planned looking at next weekend. Very cool work!

Now that talking to the HSR seems mostly solved, this makes me think about 
OpenWrt integration. Currently I see two possibities:

Integration into the kernel driver like your latest patch does.

Caveat: The build process seems to assume that all routers in the 
ar71xx/generic target share the same set of kernel modules. So patching and 
compiling yourself is no problem, but a working image on downloads.openwrt.org 
is not feasible as every router would get the HSR driver. Correct me if I am 

Or making ath9k expose the gpio and driving from user space. A generic patch 
for ath9k to register its gpio pins via the standard gpio subsystem. This 
should go upstream to the kernel and may prove usable for other access points 

An Unifi specific user space daemon listens to scan and channel change events 
via netlink (will check next weekend if channel change is broadcasted 
reliably) and tune the filter via sysfs interface accordingly like hsr.c 

Caveat: Changing ath9k driver is possibly stuff for Designated Driver. May be 
the user space component can fall back to bit banging for Chaos Calmer.

What do you think? What do OpenWrt core developers think? I'd prefer exposing 
gpio and driving from userspace.


PS: I've started working on the wiki page 
http://wiki.openwrt.org/toh/ubiquiti/unifi_outdoorplus that I hope to move to 
"supported" soon ;-)
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