On Fri, Sep 08, 2017 at 06:00:50PM +0100, Alan Young wrote: > On 08/09/17 13:27, Richard Cochran wrote: > > Last time I looked, I didn't see any way to get a useful Tx time > > stamp, due to aggregation and the opaque firmware blobs in the radio > > chips. > > > > But if you see a way in the ath9k, then by all means do it. > > Otherwise, just use NTP over wireless. > > Well, I must admit that I do not actually know much at all about wireless > drivers, but after a few hours of poking around I wonder if generating the > timestamp (immediately) after transmission might work, as this is likely to > be consistent with regard to latency.
Is there an upper bound on the latency which could be used to fix the timestamp as if it was captured before the transmission? I think there is a requirement that both SW and HW transmit timestamps are before the actual transmission. A timestamp captured after the transmission could make the measured network delay shorter than it actually is. This might be more important for NTP than PTP. -- Miroslav Lichvar ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
