linux-kernel - Re: [PATCH 0/2] Add support for Gunyah Watchdog

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Message-ID: <b105810a-63a8-4d81-9ad8-b0788e2e1431@pm.me>
Date: Mon, 22 Dec 2025 19:02:58 +0000
From: Alexander Koskovich <AKoskovich@...me>
To: Pavan Kondeti <pavan.kondeti@....qualcomm.com>, Bjorn Andersson <andersson@...nel.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, hrishabh.rajput@....qualcomm.com, Konrad Dybcio <konradybcio@...nel.org>, Wim Van Sebroeck <wim@...ux-watchdog.org>, Guenter Roeck <linux@...ck-us.net>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org, linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] Add support for Gunyah Watchdog

On 9/4/25 1:05 PM, Pavan Kondeti wrote:
> Thanks for asking this question. I believe the overlay part needs some
> discussion here.
>
> I have tried this series on 8550 MTP. The overlay failed, so watchdog
> device did not probe. same is the case with 8750 too. It works only
> after applying this patch. I will test and report my observation on 8650
> later.

Hi Pavan, was linked this thread after seeing what I think to be the 
same issue on another platform,
but issue is a bit more serious here since bootloader fails to find a 
DTB at all, not just overlay fails.
When the "arch_timer" label is missing from the base DTB on Milos, 
ufdt_apply_overlay in bootloader
will fail and it looks like the DTB memory gets corrupted. If you are 
booting without a dtbo image,
then you don't see the issue. Couple logs from bootloader when it happens:

     ApplyOverlay: ufdt apply overlay failed
     Error: Dtb overlay failed

After this happens, the DTB memory seems to get corrupted:

     ERROR: Invalid device tree header ...
     Device Tree update failed Status:Not Found

But it doesn't seem to have anything to do with the DTBO image itself 
(despite only happening with one),
as it happens even the dtbo is effectively empty with the exception of a 
dummy fixups so the old version
of libufdt in bootloader doesn't fail.

This seems to have only started happening on recent versions of the 
proprietary hypervisor (don't see any
dtb handling in https://github.com/quic/gunyah-hypervisor), since I 
don't see the same issue on Blair but I
do on Milos.

Should the label be applied to all QCOM platforms that have a timer node 
to prevent the issue from appearing
elsewhere? It looks like it's already applied to lemans & sm6150.

Thanks,
Alex