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

["Neftin, Sasha" <sasha.neftin@intel.com>]

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@dell.com wrote:
>>>> -----Original Message-----
>>>> From: Paul Menzel <pmenzel@molgen.mpg.de>
>>>> Sent: Tuesday, August 6, 2019 10:36 AM
>>>> To: Jeff Kirsher
>>>> Cc: intel-wired-lan@lists.osuosl.org; 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-graph’s 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.
> 
>>>> [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?
> Isn’t 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.