2020-04-24 09:22:19

by Wei Liu

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Subject: Questions regarding 802.11 TM and FTM in cfg80211/mac80211

Dear experts,

I am new to Linux kernel, and I have an ambitious goal to run ptp over
wireless (yes I know..  and please don't judge .. )

When I browse code in mac80211, I found function start_pmsr in
ieee80211_ops. At this moment, this function is serving a request
(defined in cfg80211) to start peer measurement, and the request seems
rather FTM specific.

Is there some code available to support the original Timing Measurement?
As I am not interested in localization/ranging, but interested in
synchronization, so the basic TM is enough for me.

Regarding FTM, the current cfg80211_pmsr_ftm_result does not contain the
ToD, ToA timestamps, it only reports the RTT. Is there a proper way to
expose these timestamps to the user space?

Thank you in advance for any guidance,

Wei