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

[Akhil P Oommen <akhilpo@oss.qualcomm.com>]

On 9/22/2025 1:51 PM, 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@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?

Lemans GPU DT patches are still in the mailing lists. Hopefully, they
will be picked up for v6.19.

-Akhil.

> 
> 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
>