linux-kernel - Re: [PATCH v3 12/12] arm64: dts: qcom: Add EL2 overlay for Lemans

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Message-ID: <20250922110602.ygduy4miw73642l6@hu-mojha-hyd.qualcomm.com>
Date: Mon, 22 Sep 2025 16:36:02 +0530
From: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
To: Stephan Gerhold <stephan.gerhold@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 12/12] arm64: dts: qcom: Add EL2 overlay for Lemans

On Mon, Sep 22, 2025 at 10:21:58AM +0200, Stephan Gerhold wrote:
> On Sun, Sep 21, 2025 at 01:11:10AM +0530, Mukesh Ojha wrote:
> > All the Lemans IOT variants boards are using Gunyah hypervisor which
> > means that, so far, Linux-based OS could only boot in EL1 on those
> > devices.  However, it is possible for us to boot Linux at EL2 on these
> > devices [1].
> > 
> > When running under Gunyah, remote processor firmware IOMMU streams is
> > controlled by the Gunyah however when Linux take ownership of it in EL2,
> > It need to configure it properly to use remote processor.
> > 
> > Add a EL2-specific DT overlay and apply it to Lemans IOT variant
> > devices to create -el2.dtb for each of them alongside "normal" dtb.
> > 
> > [1]
> > https://docs.qualcomm.com/bundle/publicresource/topics/80-70020-4/boot-developer-touchpoints.html#uefi
> > 
> > Signed-off-by: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
> > ---
> >  arch/arm64/boot/dts/qcom/Makefile        |  7 ++++++-
> >  arch/arm64/boot/dts/qcom/lemans-el2.dtso | 28 ++++++++++++++++++++++++++++
> >  2 files changed, 34 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/boot/dts/qcom/Makefile b/arch/arm64/boot/dts/qcom/Makefile
> > index 296688f7cb26..e2eb6c4f8e25 100644
> > --- a/arch/arm64/boot/dts/qcom/Makefile
> > +++ b/arch/arm64/boot/dts/qcom/Makefile
> > @@ -35,6 +35,8 @@ dtb-$(CONFIG_ARCH_QCOM)	+= lemans-evk.dtb
> >  lemans-evk-camera-csi1-imx577-dtbs	:= lemans-evk.dtb lemans-evk-camera-csi1-imx577.dtbo
> >  
> >  dtb-$(CONFIG_ARCH_QCOM)	+= lemans-evk-camera-csi1-imx577.dtb
> > +lemans-evk-el2-dtbs := lemans-evk.dtb lemans-el2.dtbo
> > +dtb-$(CONFIG_ARCH_QCOM)	+= lemans-evk-el2.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= monaco-evk.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= msm8216-samsung-fortuna3g.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= msm8916-acer-a1-724.dtb
> > @@ -136,7 +138,10 @@ dtb-$(CONFIG_ARCH_QCOM)	+= qcs6490-rb3gen2-vision-mezzanine.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= qcs8300-ride.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= qcs8550-aim300-aiot.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= qcs9100-ride.dtb
> > -dtb-$(CONFIG_ARCH_QCOM)	+= qcs9100-ride-r3.dtb
> > +qcs9100-ride-el2-dtbs := qcs9100-ride.dtb lemans-el2.dtbo
> > +dtb-$(CONFIG_ARCH_QCOM)	+= qcs9100-ride.dtb qcs9100-ride-el2.dtb
> > +qcs9100-ride-r3-el2-dtbs := qcs9100-ride-r3.dtb lemans-el2.dtbo
> > +dtb-$(CONFIG_ARCH_QCOM)	+= qcs9100-ride-r3.dtb qcs9100-ride-r3-el2.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= qdu1000-idp.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= qrb2210-rb1.dtb
> >  dtb-$(CONFIG_ARCH_QCOM)	+= qrb4210-rb2.dtb
> > diff --git a/arch/arm64/boot/dts/qcom/lemans-el2.dtso b/arch/arm64/boot/dts/qcom/lemans-el2.dtso
> > new file mode 100644
> > index 000000000000..55a2a9e2b10d
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/qcom/lemans-el2.dtso
> > @@ -0,0 +1,28 @@
> > +// SPDX-License-Identifier: BSD-3-Clause
> > +/*
> > + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> > + */
> > +
> > +/*
> > + * Lemans specific modifications required to boot in EL2.
> > + */
> > +
> > +/dts-v1/;
> > +/plugin/;
> > +
> > +/*
> > + * When running under Gunyah, remote processor firmware IOMMU streams is
> > + * controlled by the Gunyah however when we take ownership of it in EL2,
> > + * we need to configure it properly to use remote processor.
> > + */
> > +&remoteproc_adsp {
> > +	iommus = <&apps_smmu 0x3000 0x0>;
> > +};
> > +
> > +&remoteproc_cdsp0 {
> > +	iommus = <&apps_smmu 0x21c0 0x0400>;
> > +};
> > +
> > +&remoteproc_cdsp1 {
> > +	iommus = <&apps_smmu 0x29c0 0x0400>;
> > +};
> > 
> 
> Would be good to disable &iris here for now similar to
> https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/commit/?h=for-next&id=c0f045e303e014cec5d883edf82fe5de74769944
> (I'm assuming it is broken without specifying the iommus?)

You are right, I should disable all the subsystem which is not tested
to work as of now.

> 
> What about GPU? You can load the GPU zap shader in EL2 without further
> changes in the drm/msm driver?
> 
> What about &remoteproc_gpdsp0 and &remoteproc_gpdsp1?

gpu, gpdsp0, gpdsp1 should be disabled for now.

> 
> Please make the changes in a way that they result in a properly
> functional boot without errors. Disable functionality that needs
> more work before it can be enabled in EL2.

Sure, thank you.

> 
> Thanks,
> Stephan

-- 
-Mukesh Ojha