netdev - Re: [Intel-wired-lan] [PATCH 2/3] e1000e: Make mei

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Date:   Wed, 14 Jul 2021 17:52:18 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     "Ruinskiy, Dima" <dima.ruinskiy@...el.com>
Cc:     Sasha Neftin <sasha.neftin@...el.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        AceLan Kao <acelan.kao@...onical.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "moderated list:INTEL ETHERNET DRIVERS" 
        <intel-wired-lan@...ts.osuosl.org>,
        "David S. Miller" <davem@...emloft.net>,
        devora.fuxbrumer@...el.com, alexander.usyskin@...el.com
Subject: Re: [Intel-wired-lan] [PATCH 2/3] e1000e: Make mei_me active when
 e1000e is in use

On Wed, Jul 14, 2021 at 5:06 PM Ruinskiy, Dima <dima.ruinskiy@...el.com> wrote:
>
> On 14/07/2021 9:28, Kai-Heng Feng wrote:
> >> I do not know how MEI driver affect 1Gbe driver - so, I would suggest to
> >> involve our CSME engineer (alexander.usyskin@...el.com) and try to
> >> investigate this problem.
> >> Does this problem observed on Dell systems? As I heard no reproduction
> >> on Intel's RVP platform.
> >> Another question: does disable mei_me runpm solve your problem?
> >
> > Yes, disabling runpm on mei_me can workaround the issue, and that's
> > essentially what this patch does by adding DL_FLAG_PM_RUNTIME |
> > DL_FLAG_RPM_ACTIVE flag.
> >
> > Kai-Heng
> Hi, Kai-Heng,
>
> If the goal of the patch is to essentially disable runpm on mei_me, then
> why is the patch touching code in the e1000e driver?

We can put the workaround in e1000e, mei_me or as PCI quirk.
But since the bug itself manifests in e1000e, I think it's more
appropriate to put it here.

To be more specific, it doesn't disable runtime suspend on mei_me, it
makes mei_me the power supplier of e1000e.
So when e1000e can be runtime suspended (i.e. no link partner), mei_me
can also get runtime suspended too.

>
> I agree with Sasha Neftin; it seems like the wrong location, and the
> wrong way to do it, even if it currently works. We need to understand
> what causes runpm of mei_me to adversely affect LAN Rx, and for this we
> need the involvement of mei_me owners.

I think it's the right location, however I totally agree with your
other arguments.
There are many users already affected by this bug, so if a proper fix
isn't available for now, the temporary workaround can help here.

Kai-Heng

>
> --Dima
> ---------------------------------------------------------------------
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