linux-kernel - Re: [BUG] Warning and NULL-ptr dereference in amdgpu driver with 5.18

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Date:   Thu, 12 May 2022 20:15:08 +0200
From:   Jörg Rödel <jroedel@...e.de>
To:     Alex Deucher <alexdeucher@...il.com>
Cc:     "Wentland, Harry" <Harry.Wentland@....com>,
        "Siqueira, Rodrigo" <Rodrigo.Siqueira@....com>,
        "Kazlauskas, Nicholas" <nicholas.kazlauskas@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian Koenig <christian.koenig@....com>,
        xinhui pan <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] Warning and NULL-ptr dereference in amdgpu driver with 5.18

On Thu, May 12, 2022 at 09:47:29AM -0400, Alex Deucher wrote:
> Are those new?  Maybe the card is not seated correctly?  Can you try
> another slot?

I can't remember having seen these TLP error messages with older
kernels. 5.17 still works fine with this card.

I will try to put the card into another slot tomorrow.

> As for the null pointer defer in the display code, @Wentland, Harry
> any ideas?  I don't see why that should happen.  Maybe some hotplug
> pin is faulty or the display has input detection and that is causing
> some sort of hotplug interrupt that causes a race somewhere in the
> driver?  Can you make sure the monitor connector is firmly seated on
> the GPU?

The connectors are fine, the displays are connected via miniDP on the
GPU and DP on the display side. On the other hand my monitors do not
seem to have the highest quality. Occassionally the resolution is
wrongly detected or DP signal is lost. I am not sure why, I suspect
there is some interference between the two DP cables. But this is a
problem for as long as I have these two monitors, the NULL-ptr deref
only happens with v5.18.

Regards,

-- 
Jörg Rödel
jroedel@...e.de

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