linux-kernel - Re: [RFC PATCH] pci: prevent putting pcie devices into lower device states on certain intel bridges

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Message-ID: <CACO55tvjFPAMgz6DMGmJQ3adtJBX6yYnFRO9gVBEpMVTEBu0og@mail.gmail.com>
Date:   Tue, 1 Oct 2019 18:21:28 +0200
From:   Karol Herbst <kherbst@...hat.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Lyude Paul <lyude@...hat.com>,
        Linux PCI <linux-pci@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        nouveau <nouveau@...ts.freedesktop.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [RFC PATCH] pci: prevent putting pcie devices into lower device
 states on certain intel bridges

On Tue, Oct 1, 2019 at 3:27 PM Bjorn Helgaas <helgaas@...nel.org> wrote:
>
> On Mon, Sep 30, 2019 at 06:36:12PM +0200, Karol Herbst wrote:
> > On Mon, Sep 30, 2019 at 6:30 PM Mika Westerberg
> > <mika.westerberg@...ux.intel.com> wrote:
> > >
> > > On Mon, Sep 30, 2019 at 06:05:14PM +0200, Karol Herbst wrote:
> > > > still happens with your patch applied. The machine simply gets shut down.
> > > >
> > > > dmesg can be found here:
> > > > https://gist.githubusercontent.com/karolherbst/40eb091c7b7b33ef993525de660f1a3b/raw/2380e31f566e93e5ba7c87ef545420965d4c492c/gistfile1.txt
> > >
> > > Looking your dmesg:
> > >
> > > Sep 30 17:24:27 kernel: nouveau 0000:01:00.0: DRM: DCB version 4.1
> > > Sep 30 17:24:27 kernel: nouveau 0000:01:00.0: DRM: MM: using COPY for buffer copies
> > > Sep 30 17:24:27 kernel: [drm] Initialized nouveau 1.3.1 20120801 for 0000:01:00.0 on minor 1
> > >
> > > I would assume it runtime suspends here. Then it wakes up because of PCI
> > > access from userspace:
> > >
> > > Sep 30 17:24:42 kernel: pci_raw_set_power_state: 56 callbacks suppressed
> > >
> > > and for some reason it does not get resumed properly. There are also few
> > > warnings from ACPI that might be relevant:
> > >
> > > Sep 30 17:24:27 kernel: ACPI Warning: \_SB.PCI0.GFX0._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20190509/nsarguments-59)
> > > Sep 30 17:24:27 kernel: ACPI Warning: \_SB.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20190509/nsarguments-59)
> >
> > afaik this is the case for essentially every laptop out there.
>
> I think we should look into this a little bit.
> acpi_ns_check_argument_types() checks the argument type and prints
> this message, but AFAICT it doesn't actually fix anything or prevent
> execution of the method, so I have no idea what happens when we
> actually execute the _DSM.
>

I can assure you that this warning happens on every single laptop out
there with dual Nvidia graphics and it's essentially just a firmware
bug. And it never caused any issues on any of the older laptops (or
newest one for that matter).

> If we execute this _DSM as part of power management, and the _DSM
> doesn't work right, it would be no surprise that we have problems.
>
> Maybe we could learn something by turning on ACPI_DB_PARSE output (see
> Documentation/firmware-guide/acpi/debug.rst).
>
> You must have an acpidump already from all your investigation.  Can
> you put it somewhere, e.g., bugzilla.kernel.org, and include a URL?

Will do so later, right now I am traveling to XDC and will have more
time for that then.