linux-kernel - Re: [PATCH v4] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges

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Date:   Wed, 20 Nov 2019 13:11:52 +0100
From:   Karol Herbst <kherbst@...hat.com>
To:     Mika Westerberg <mika.westerberg@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Bjorn Helgaas <helgaas@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Lyude Paul <lyude@...hat.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        nouveau <nouveau@...ts.freedesktop.org>,
        Dave Airlie <airlied@...il.com>,
        Mario Limonciello <Mario.Limonciello@...l.com>
Subject: Re: [PATCH v4] pci: prevent putting nvidia GPUs into lower device
 states on certain intel bridges

On Wed, Nov 20, 2019 at 1:09 PM Mika Westerberg
<mika.westerberg@...el.com> wrote:
>
> On Wed, Nov 20, 2019 at 12:58:00PM +0100, Karol Herbst wrote:
> > overall, what I really want to know is, _why_ does it work on windows?
>
> So do I ;-)
>
> > Or what are we doing differently on Linux so that it doesn't work? If
> > anybody has any idea on how we could dig into this and figure it out
> > on this level, this would probably allow us to get closer to the root
> > cause? no?
>
> Have you tried to use the acpi_rev_override parameter in your system and
> does it have any effect?
>
> Also did you try to trace the ACPI _ON/_OFF() methods? I think that
> should hopefully reveal something.
>

I think I did in the past and it seemed to have worked, there is just
one big issue with this: it's a Dell specific workaround afaik, and
this issue plagues not just Dell, but we've seen it on HP and Lenovo
laptops as well, and I've heard about users having the same issues on
Asus and MSI laptops as well.

I will spend some time to collect all the necessary information,
create a bug to put it all in there and send out a v5 with the updated
information and references to this bug.