Re: [PATCH] r8169: don't use MSI-X on RTL8106e

[Bjorn Helgaas]

[+cc Marc, Thomas, Christoph, linux-pci)
(beginning of thread at [1])

On Thu, Aug 16, 2018 at 09:50:48PM +0200, Heiner Kallweit wrote:
> On 16.08.2018 21:39, David Miller wrote:
> > From: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> > Date: Thu, 16 Aug 2018 21:37:31 +0200
> > 
> >> On 16.08.2018 21:21, David Miller wrote:
> >>> From: <jian-hong@xxxxxxxxxxxx>
> >>> Date: Wed, 15 Aug 2018 14:21:10 +0800
> >>>
> >>>> Found the ethernet network on ASUS X441UAR doesn't come back on resume
> >>>> from suspend when using MSI-X.  The chip is RTL8106e - version 39.
> >>>
> >>> Heiner, please take a look at this.
> >>>
> >>> You recently disabled MSI-X on RTL8168g for similar reasons.
> >>>
> >>> Now that we've seen two chips like this, maybe there is some other
> >>> problem afoot.
> >>>
> >> Thanks for the hint. I saw it already and just contacted Realtek
> >> whether they are aware of any MSI-X issues with particular chip
> >> versions. With the chip versions I have access to MSI-X works fine.
> >>
> >> There's also the theoretical option that the issues are caused by
> >> broken BIOS's. But so far only chip versions have been reported
> >> which are very similar, at least with regard to version number
> >> (2x VER_40, 1x VER_39). So they may share some buggy component.
> >>
> >> Let's see whether Realtek can provide some hint.
> >> If more chip versions are reported having problems with MSI-X,
> >> then we could switch to a whitelist or disable MSI-X in general.
> > 
> > It could be that we need to reprogram some register(s) on resume,
> > which normally might not be needed, and that is what is causing the
> > problem with some chips.
> > 
> Indeed. That's what I'm checking with Realtek.
> In the register list in the r8169 driver there's one entry which
> seems to indicate that there are MSI-X specific settings.
> However this register isn't used, and the r8168 vendor driver
> uses only MSI. And there are no public datasheets.

Do we have any information about these chip versions in other systems?
Or other devices using MSI-X in the same ASUS system?  It seems
possible that there's some PCI core or suspend/resume issue with MSI-X
and this patch just avoids it without fixing the root cause.

It might be useful to have a kernel.org bugzilla with the complete
dmesg, "sudo lspci -vv" output, and /proc/interrupts contents archived
for future reference.

[1] https://lkml.kernel.org/r/20180815062110.16155-1-jian-hong@xxxxxxxxxxxx