On Tue, Jul 14, 2020 at 05:26:28PM +0100, Russell King wrote: > Add PTP basic support for Marvell 88E151x PHYs. These PHYs support > timestamping the egress and ingress of packets, but does not support > any packet modification, nor do we support any filtering beyond > selecting packets that the hardware recognises as PTP/802.1AS.
A question has come up concerning the selection of PTP timestamping sources within a network device. I have the situation on a couple of devices where there are multiple places that can do PTP timestamping: - the PHY (slow to access, only event capture which may not be wired, doesn't seem to synchronise well - delay of 58000, frequency changes every second between +/-1500ppb.) - the Ethernet MAC (fast to access, supports event capture and trigger generation which also may not be wired, synchronises well, delay of 700, frequency changes every second +/- 40ppb.) How do we deal with this situation - from what I can see from the ethtool API, we have to make a choice about which to use. How do we make that choice? It's not a case of "just implement one" since hardware may have both available on a particular ethernet interface or just one available. Do we need a property to indicate whether we wish to use the PHY or MAC PTP stamping, or something more elaborate? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
