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

[Neftin, Sasha]

On 8/7/2019 17:55, Paul Menzel wrote:
> Dear Sasha,
>
>
> On 07.08.19 09:23, Neftin, Sasha wrote:
> > 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
> > > >
> > > >  ÂÂÂÂ $ lspci -nn -s 00:1f.6
> > > >  ÂÂÂÂ 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]:
> > > >
> > > >  ÂÂÂÂÂÂÂÂ for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ udelay(50);
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ mdic = er32(MDIC);
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ if (mdic & E1000_MDIC_READY)
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ break;
> > > >  ÂÂÂÂÂÂÂÂ }
> > > >  ÂÂÂÂÂÂÂÂ if (!(mdic & E1000_MDIC_READY)) {
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ e_dbg("MDI Read did not complete\n");
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return -E1000_ERR_PHY;
> > > >  ÂÂÂÂÂÂÂÂ }
> > > >  ÂÂÂÂÂÂÂÂ if (mdic & E1000_MDIC_ERROR) {
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ e_dbg("MDI Error\n");
> > > >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return -E1000_ERR_PHY;
> > > >  ÂÂÂÂÂÂÂÂ }
> > > >
> > > > Unfortunately, errors are not logged if dynamic debug is disabled,
> > > > so rebuilding the Linux kernel with `CONFIG_DYNAMIC_DEBUG`, and
> > > >
> > > >  ÂÂÂÂ echo "file drivers/net/ethernet/* +p" | sudo tee
> > > > /sys/kernel/debug/dynamic_debug/control
> > > >
> > > > I got the messages below.
> > > >
> > > >  ÂÂÂÂ [ 4159.204192] e1000e 0000:00:1f.6 net00: MDI Error
> > > >  ÂÂÂÂ [ 4160.267950] e1000e 0000:00:1f.6 net00: MDI Write did not complete
> > > >  ÂÂÂÂ [ 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.
>
> > > > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/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/
>
> I can try that in the next days.
>
> > We are using external PHY. Required ~200 ms to complete MDIC
> > transaction (depended on the project).
>
> Are you referring to the out-of-tree driver?
I believe the out of tree driver have a same approach to MDIC access.
> > 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.
> My point was more, if you know that more time is needed, before the MDI
> setting(?) will succeed, why try it anyway and go into the error paths?
> Isnât there some polling possible to find out, when MDI can be set up?
e1000e is very old driver and serve pretty lot of 1G clients. Each 1Gbe 
MAC/PHY controller have a different configuration depend platform.
> Kind regards,
>
> Paul
Hello Paul,
Let me back later with more information specific your device. I will try 
find out more details with design team.