Hi, I'm trying to get hardware timestamps for received packets on a 82579LM (PCI id 8086:1502). I do get timestamps, but the time advances by a factor of 3.84 too fast. In the datasheet on page 132 it says "The clock used has stable 96MHz or 25Mhz frequency", but not which (there is no other mention of these frequencies in the data sheet). The driver reads bit 5 of TSYNCRXCTL, which is reserved for 82579, but documented as SYSCFI for i217, with 0: 25MHz and 1: 96MHz. The Linux driver e1000e decides based on this flag between 25 and 96 MHz, apparently it wrongly chooses 25MHz instead of 96MHz in my case (netdev.c, e1000e_get_base_timinca(), case e1000_pch2lan).
I see that the clock is enabled before reading the flag for i217 and similar, but not for 82579, could that be a factor? If yes, how should it be fixed? I’m using Linux 4.4, but I don't see any significant differences to 4.9 in this code. Regards Jürgen -- Jürgen Stuber Software Developer Core Real Time Implementation dSPACE GmbH, Rathenaustr. 26, 33102 Paderborn, Germany http://www.dspace.de mailto:jstuber.h...@dspace.de ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
