linux-kernel - Re: [PATCH 3/3] arm64: dts: qcom: sm8550: Fix DTBO boot failure

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Message-ID: <CALHNRZ80+KAfm2YHEoodBv_7jDZPZjtr-koo7q_N+aX+i1OfnA@mail.gmail.com>
Date: Sat, 31 Jan 2026 03:09:12 -0600
From: Aaron Kling <webgeek1234@...il.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
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 3/3] arm64: dts: qcom: sm8550: Fix DTBO boot failure

On Sat, Jan 31, 2026 at 1:47 AM Dmitry Baryshkov
<dmitry.baryshkov@....qualcomm.com> wrote:
>
> On Thu, Jan 29, 2026 at 01:46:32AM -0600, 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:
> >
> > * The scm node must be named qcom_scm
> > * 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.
> >
> > Signed-off-by: Aaron Kling <webgeek1234@...il.com>
>
> Did Pavan provide an SoB to the patch?

No. The change comes from the gunyah watchdog discussion here [0].

>
> > ---
> >  arch/arm64/boot/dts/qcom/sm8550.dtsi | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/sm8550.dtsi b/arch/arm64/boot/dts/qcom/sm8550.dtsi
> > index 740e3c238e8ed0f162dd168291f6e307ace66e80..d7cc20e1931904e7c603b800089f00955ecec3b7 100644
> > --- a/arch/arm64/boot/dts/qcom/sm8550.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sm8550.dtsi
> > @@ -329,7 +329,7 @@ cluster_sleep_1: cluster-sleep-1 {
> >       };
> >
> >       firmware {
> > -             scm: scm {
> > +             scm: qcom_scm {
>
> This one is a definite no-go. Device nodes can't use underscores in
> names. It has been told to Qualcomm for ages. If we didn't comply, it
> doesn't give us a permission to break the rules.

I have not been able to make ABL load a dtbo without this change so
far, though I have had a suggestion from off list that I may need to
try a different method of flashing changes. I have not yet had time to
do so yet, however. Given this list came from a Qualcomm employee and
worked as advertised, my tendency is to believe that it is the minimal
required.

The devices I am working on are not fused and thus I do have the
capability to use a custom ABL with fixes. However, doing so would
make the user transition from the stock os to a custom one more
complicated. Plus this affects many devices that are fused and thus do
not have such an option.

In the likely case that the bootloader dtbo functionality does indeed
require this change, and the mainline kernel cannot accept it, then
what are the options? My use case involves using out of tree dtbs that
include the mainline dtsi's. I could do a delete-node on scm and add
it back as qcom_scm, but I would very highly prefer not to. The less
downstream changes I have to carry, the less work I need to do to keep
up to date. And on the other side, getting android vendors to update
their ABL seems extremely unlikely.

>
> >                       compatible = "qcom,scm-sm8550", "qcom,scm";
> >                       qcom,dload-mode = <&tcsr 0x19000>;
> >                       interconnects = <&aggre2_noc MASTER_CRYPTO QCOM_ICC_TAG_ALWAYS
> > @@ -6764,7 +6764,7 @@ trip-point2 {
> >               };
> >       };
> >
> > -     timer {
> > +     arch_timer: timer {
>
> Please add a comment, otherwise somebody might decide to drop the unused
> label.

Ack.

Aaron

[0] https://lore.kernel.org/all/91002189-9d9e-48a2-8424-c42705fed3f8@quicinc.com/