Re: [Intel-wired-lan] MDI errors during resume from ACPI S3 (suspend to ram)

[Neftin, Sasha]

On 8/6/2019 18:53, Mario.Limonciello@xxxxxxxx wrote:
> > -----Original Message-----
> > From: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
> > Sent: Tuesday, August 6, 2019 10:36 AM
> > To: Jeff Kirsher
> > Cc: intel-wired-lan@xxxxxxxxxxxxxxxx; Linux Kernel Mailing List; Limonciello, Mario
> > Subject: MDI errors during resume from ACPI S3 (suspend to ram)
> >
> > Dear Linux folks,
> >
> >
> > Trying to decrease the resume time of Linux 5.3-rc3 on the Dell OptiPlex
> > 5040 with the device below
> >
> >      $ lspci -nn -s 00:1f.6
> >      00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (2)
> > I219-V [8086:15b8] (rev 31)
> >
> > pm-graphâs script `sleepgraph.py` shows, that the driver *e1000e* takes
> > around 400 ms, which is quite a lot. The call graph trace shows that
> > `e1000e_read_phy_reg_mdic()` is responsible for a lot of those. From
> > `drivers/net/ethernet/intel/e1000e/phy.c` [1]:
> >
> >          for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
> >                  udelay(50);
> >                  mdic = er32(MDIC);
> >                  if (mdic & E1000_MDIC_READY)
> >                          break;
> >          }
> >          if (!(mdic & E1000_MDIC_READY)) {
> >                  e_dbg("MDI Read did not complete\n");
> >                  return -E1000_ERR_PHY;
> >          }
> >          if (mdic & E1000_MDIC_ERROR) {
> >                  e_dbg("MDI Error\n");
> >                  return -E1000_ERR_PHY;
> >          }
> >
> > Unfortunately, errors are not logged if dynamic debug is disabled,
> > so rebuilding the Linux kernel with `CONFIG_DYNAMIC_DEBUG`, and
> >
> >      echo "file drivers/net/ethernet/* +p" | sudo tee
> > /sys/kernel/debug/dynamic_debug/control
> >
> > I got the messages below.
> >
> >      [ 4159.204192] e1000e 0000:00:1f.6 net00: MDI Error
> >      [ 4160.267950] e1000e 0000:00:1f.6 net00: MDI Write did not complete
> >      [ 4160.359855] e1000e 0000:00:1f.6 net00: MDI Error
> >
> > Can you please shed a little more light into these errors? Please
> > find the full log attached.
> >
> >
> > Kind regards,
> >
> > Paul
> >
> >
> > [1]:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/n
> > et/ethernet/intel/e1000e/phy.c#n206
>
> Strictly as a reference point you may consider trying the out-of-tree driver to see if these
> behaviors persist.
>
> https://sourceforge.net/projects/e1000/
>
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We are using external PHY. Required ~200 ms to complete MDIC transaction 
(depended on the project). You need to take to consider this time before 
access to the PHY. I do not recommend decrease timer in a 
'e1000e_read_phy_reg_mdic()' method. We could hit on wrong MDI access.