linux-kernel - Re: [PATCH v2] arm64: dts: qcom: sm8550: Fix DTBO boot failure

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Message-ID: <CALHNRZ9k3yxXb9OfYXMSfEwyYKU8Rrrrjb-hPqLgU90X9YBP8g@mail.gmail.com>
Date: Sun, 8 Feb 2026 09:10:21 -0600
From: Aaron Kling <webgeek1234@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Kumar Sharma <quic_vksharma@...cinc.com>, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Pavan Kondeti <pavan.kondeti@....qualcomm.com>
Subject: Re: [PATCH v2] arm64: dts: qcom: sm8550: Fix DTBO boot failure

On Sun, Feb 8, 2026 at 3:07 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> On 08/02/2026 02:16, Aaron Kling via B4 Relay wrote:
> > From: Pavan Kondeti <pavan.kondeti@....qualcomm.com>
> >
> > ABL requires certain things in the base dtb to apply a dtbo. Namely:
> >
> > * A label named qcom_tzlog must exist, but doesn't have to contain any
> >   specific properties
> > * The timer node must have a label named arch_timer
> >
> > This aligns the sm8550 soc dtsi with those requirements. Without these
> > in the base dtb, when ABL attempts to apply any dtbo, it will fail to
> > the bootloader menu.
> >
>
> Incomplete DCO chain.
>
> > Co-authored-by: Aaron Kling <webgeek1234@...il.com>
> > Signed-off-by: Aaron Kling <webgeek1234@...il.com>
> > ---
> > With a current mainline sm8550 base dtb, ABL will fail to apply any dtbo
> > and fail back to the bootloader menu. There are two changes needed:
>
> Since when? We were testing SM8550 (me on QRD) all the time and there
> was no problem.
>
> You need to provide details which hardware needs it, if this is about to
> expected, but honestly, we don't add such nodes/labels for downstream
> bootloader. Qualcomm should fix the bootloder instead.

This discussion has been ongoing in a couple places. It is needed on
all semi-recent recent qcom socs. See this chain [0] on my sm8550
questions thread and the previous revision of this series [1]. This
has been a known issue for a while, see this comment [2] on the gunyah
watchdog series, which is what the series was based on.

My current understanding is that the qcom_tzlog and arch_timer labels
are required period for abl to apply a dtbo. And this setup will only
work flashing a unit from a downstream dtb to mainline with this
change if said unit is removed from all external power and fully
powered off. For this to work without a cold restart, the scm node
needs renamed to qcom_scm. This latter part was rejected during v1.

Aaron

[0] https://lore.kernel.org/linux-arm-msm/aa90c5ca-72d7-48fb-b3b6-4be8a51dc0cc@oss.qualcomm.com/
[1] https://lore.kernel.org/linux-arm-msm/20260129-sm8550-abl-dtbo-v1-0-abca3be14024@gmail.com/
[2] https://lore.kernel.org/all/91002189-9d9e-48a2-8424-c42705fed3f8@quicinc.com/