[PATCH 0/1][SRU][N][P] integrated I219-LM network adapter appears to be running too fast, causing synchronization issues when using the I219-LM PTP feature

[AceLan Kao]

From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2116072

[Impcat]
There is an issue on Dell Precision 3591 running. The PHC(PTP Hardware
Clock) on the integrated I219-LM network adapter appears to be running too
fast, causing synchronization issues when using the I219-LM PTP feature.

[Fix]
Intel submits a patch to fix the clock issue which is included in v6.16-rc3
688a0d61b2d7 e1000e: set fixed clock frequency indication for Nahum 11 and Nahum 13

[Test]
Installed linuxptp (Version 4.4+snap):
$ sudo snap install --edge linuxptp

Run this command to do a sanity check of the PHC (resetting clock to 0.0
time, waiting for 10 seconds, and then reading time. The time read back
should be (roughly) 10 seconds):
$ sudo linuxptp.phc-ctl enp0s31f6 freq 0 set 0.0 wait 10.0 get
phc_ctl[1461.965]: adjusted clock frequency offset to 0.000000ppb
phc_ctl[1461.965]: set clock time to 0.000000000 or Thu Jan 1 01:00:00 1970
phc_ctl[1471.965]: process slept for 10.000000 seconds
phc_ctl[1471.965]: clock time is 15.998421125 or Thu Jan 1 01:00:15 1970

The returned time should be around 10 seconds.
Without the fix, it's around 16 seconds.

[Where problems could occur]
Fixed the clock value, and ignore the value from the firmware on mtp, lnp,
and ptp platforms.
It won't introduce any issue, because the clock is alwyas 38.4MHz on those
platforms.

Vitaly Lifshits (1):
  e1000e: set fixed clock frequency indication for Nahum 11 and Nahum 13

 drivers/net/ethernet/intel/e1000e/netdev.c | 14 +++++++++++---
 drivers/net/ethernet/intel/e1000e/ptp.c    |  8 +++++---
 2 files changed, 16 insertions(+), 6 deletions(-)

-- 
2.43.0