http://bugzilla.suse.com/show_bug.cgi?id=1075876
http://bugzilla.suse.com/show_bug.cgi?id=1075876#c15
Benjamin Poirier
Created attachment 768018 [details] Test with kernel 4.4.127-4.g662314f-default
That's very interesting. I thought the problem would occur only at boot but it seems it can happen any time TSYNCRXCTL is read.
Dear Benjamin, thanks a lot! Seems to work.
Since I'd like to understand a bit more, may I ask some questions?
Why does it sometimes need a second attempt to get a response from "er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI" in netdev.c? Your test would try up to ten times but up to now I only observed failed first attempts.
The intel 82574 datasheet (§10.2.9.1) contains information about the TSYNCRXCTL register but bit 5 (E1000_TSYNCRXCTL_SYSCFI) is simply marked "Reserved". From comments removed in commit 83129b37ef35 ("e1000e: fix systim issues"), SYSCFI stands for "System Clock Frequency Indication". From the comment "Stable 24MHz frequency" I assumed that it reads 1 once the clock has had enough time to initialize and be stable but I'm not so sure anymore after seeing the log in comment 14. I don't know why it works sometimes but not others, 10x100ms tries just seemed like reasonable values to try. I don't know if the behavior we observed is intentional or not. I will raise the question on the intel-wired-lan mailing list but first, ...
Does this problem only affect kernel 4.4 and is not happening in newer kernels? The code in file netdev.c, function e1000e_get_base_timinca looks unchanged for me when accessing the adapter variant "spt".
... I wonder about the same thing. I also looked at the code paths and came to the same conclusion. It seems like the following could be reports of the same problem on more recent kernels: https://bugzilla.redhat.com/show_bug.cgi?id=1463882 https://bugzilla.redhat.com/show_bug.cgi?id=1431863 If you don't mind testing another kernel, I've prepared a kernel package in project home:benjamin_poirier:bsc1075876, based on the "master" openSUSE branch (v4.16) with a similar debugging patch. Could you please try it and report if you see the "No SYSCFI in TSYNCRXCTL" message with this kernel? https://download.opensuse.org/repositories/home:/benjamin_poirier:/bsc107587... -- You are receiving this mail because: You are on the CC list for the bug.