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

[Stephan Gerhold <stephan.gerhold@linaro.org>]

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@oss.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?)

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?

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.

Thanks,
Stephan