On Tue, Jun 04, 2024 at 09:13:56AM -0400, Mateusz Polchlopek wrote: > From: Jacob Keller <jacob.e.kel...@intel.com> > > The Rx timestamps reported by hardware may only have 32 bits of storage > for nanosecond time. These timestamps cannot be directly reported to the > Linux stack, as it expects 64bits of time. > > To handle this, the timestamps must be extended using an algorithm that > calculates the corrected 64bit timestamp by comparison between the PHC > time and the timestamp. This algorithm requires the PHC time to be > captured within ~2 seconds of when the timestamp was captured. > > Instead of trying to read the PHC time in the Rx hotpath, the algorithm > relies on a cached value that is periodically updated. > > Keep this cached time up to date by using the PTP .do_aux_work kthread > function. > > The iavf_ptp_do_aux_work will reschedule itself about twice a second, > and will check whether or not the cached PTP time needs to be updated. > If so, it issues a VIRTCHNL_OP_1588_PTP_GET_TIME to request the time > from the PF. The jitter and latency involved with this command aren't > important, because the cached time just needs to be kept up to date > within about ~2 seconds. > > Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com> > Reviewed-by: Wojciech Drewek <wojciech.dre...@intel.com> > Co-developed-by: Mateusz Polchlopek <mateusz.polchlo...@intel.com> > Signed-off-by: Mateusz Polchlopek <mateusz.polchlo...@intel.com>
Reviewed-by: Simon Horman <ho...@kernel.org>
