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> On Feb 07, 2017, at 06:01, Miroslav Lichvar <mlich...@redhat.com> wrote: > > 5) new SO_TIMESTAMPING options to get transposed RX timestamps > > PTP uses preamble RX timestamps, but NTP works with trailer RX > timestamps. This means NTP implementations currently need to > transpose HW RX timestamps. The calculation requires the link speed > and the length of the packet at layer 2. It seems this can be > reliably done only using raw sockets. It would be very nice if the > kernel could tranpose the timestamps automatically. > > The existing SOF_TIMESTAMPING_RX_HARDWARE flag could be aliased to > SOF_TIMESTAMPING_RX_HARDWARE_PREAMBLE and the new flag could be > SOF_TIMESTAMPING_RX_HARDWARE_TRAILER. > > PTP has a similar problem with SW RX timestamps, which are closer > to the trailer timestamps rather than preamble timestamps. A new > SOF_TIMESTAMPING_RX_SOFTWARE_PREAMBLE flag could be added for PTP > implementations to get transposed timestamps in order to improve > accuracy. > > 6) new SO_TIMESTAMPING option to get PHC index with HW timestamps > > With bridges, bonding and other things it's difficult to determine > which PHC timestamped the packet. It would be very useful if the > PHC index was provided with each HW timestamp. > > I'm not sure what would be the best place to put it. I guess the > second timespec in scm_timestamping could be reused for this, but > that sounds like a gross hack. Do we need to define a new struct? Miroslav, if #5 were implemented, would #6 still needed? Denny
