diff options
Diffstat (limited to 'Documentation/networking/timestamping.txt')
| -rw-r--r-- | Documentation/networking/timestamping.txt | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt index bc3554124903..897f942b976b 100644 --- a/Documentation/networking/timestamping.txt +++ b/Documentation/networking/timestamping.txt @@ -40,7 +40,7 @@ the set bits correspond to data that is available, then the control message will not be generated: SOF_TIMESTAMPING_SOFTWARE: report systime if available -SOF_TIMESTAMPING_SYS_HARDWARE: report hwtimetrans if available +SOF_TIMESTAMPING_SYS_HARDWARE: report hwtimetrans if available (deprecated) SOF_TIMESTAMPING_RAW_HARDWARE: report hwtimeraw if available It is worth noting that timestamps may be collected for reasons other @@ -88,13 +88,12 @@ hwtimeraw is the original hardware time stamp. Filled in if SOF_TIMESTAMPING_RAW_HARDWARE is set. No assumptions about its relation to system time should be made. -hwtimetrans is the hardware time stamp transformed so that it -corresponds as good as possible to system time. This correlation is -not perfect; as a consequence, sorting packets received via different -NICs by their hwtimetrans may differ from the order in which they were -received. hwtimetrans may be non-monotonic even for the same NIC. -Filled in if SOF_TIMESTAMPING_SYS_HARDWARE is set. Requires support -by the network device and will be empty without that support. +hwtimetrans is always zero. This field is deprecated. It used to hold +hw timestamps converted to system time. Instead, expose the hardware +clock device on the NIC directly as a HW PTP clock source, to allow +time conversion in userspace and optionally synchronize system time +with a userspace PTP stack such as linuxptp. For the PTP clock API, +see Documentation/ptp/ptp.txt. SIOCSHWTSTAMP, SIOCGHWTSTAMP: @@ -185,7 +184,6 @@ struct skb_shared_hwtstamps { * since arbitrary point in time */ ktime_t hwtstamp; - ktime_t syststamp; /* hwtstamp transformed to system time base */ }; Time stamps for outgoing packets are to be generated as follows: |