Re: [PATCH v2 2/2] arm64: dts: qcom: shikra: Add EL2 overlay for remoteproc SMMU mappings

[Komal Bajaj <komal.bajaj@oss.qualcomm.com>]

On 9/30/2026 5:25 PM, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [Medium] Missing EL2 targets for camera EVK variants
> - [Medium] Undocumented disablement of GPU zap shader in EL2 overlay
> --
>
> commit 07c9abdfac5fabfba8cfb72f094624db1d5cb41b
> Author: Komal Bajaj <komal.bajaj@oss.qualcomm.com>
>
> arm64: dts: qcom: shikra: Add EL2 overlay for remoteproc SMMU mappings
>
> This commit introduces an EL2-specific DeviceTree overlay for Shikra boards.
> It explicitly configures the firmware IOMMU streams for remote processors,
> allowing Linux to boot directly at EL2 without a hypervisor.
>
>> diff --git a/arch/arm64/boot/dts/qcom/Makefile b/arch/arm64/boot/dts/qcom/Makefile
>> index 4e714251d5e6b..634914b8f229b 100644
>> --- a/arch/arm64/boot/dts/qcom/Makefile
>> +++ b/arch/arm64/boot/dts/qcom/Makefile
> [ ... ]
>> @@ -377,6 +388,7 @@ shikra-iqs-evk-imx577-camera-dtbs	:= shikra-iqs-evk.dtb shikra-iqs-evk-imx577-ca
>>   dtb-$(CONFIG_ARCH_QCOM)	+= shikra-cqm-evk-imx577-camera.dtb
>>   dtb-$(CONFIG_ARCH_QCOM)	+= shikra-cqs-evk-imx577-camera.dtb
>>   dtb-$(CONFIG_ARCH_QCOM)	+= shikra-iqs-evk-imx577-camera.dtb
> [Severity: Medium]
> The commit message states the overlay is applied to "all Shikra EVK variants
> devices", but are we missing the EL2 targets for these camera variants?
>
> Without adding targets like shikra-cqm-evk-imx577-camera-el2-dtbs, the camera
> variants cannot be built or booted natively at EL2.

Camera variants have not yet been validated in EL2, so the corresponding 
*-el2-dtbs targets were not added.
We will add them in a follow-up change once EL2 validation is completed.

>> +
>>   dtb-$(CONFIG_ARCH_QCOM)	+= sm4250-oneplus-billie2.dtb
> [ ... ]
>
>> diff --git a/arch/arm64/boot/dts/qcom/shikra-el2.dtso b/arch/arm64/boot/dts/qcom/shikra-el2.dtso
>> new file mode 100644
>> index 0000000000000..d2f3186bd47db
>> --- /dev/null
>> +++ b/arch/arm64/boot/dts/qcom/shikra-el2.dtso
>> @@ -0,0 +1,23 @@
>> +// SPDX-License-Identifier: BSD-3-Clause
>> +/*
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
>> + *
>> + * Shikra specific modifications required to boot in EL2.
>> + */
>> +
>> +/dts-v1/;
>> +/plugin/;
>> +
>> +&gpu_zap_shader {
>> +	status = "disabled";
>> +};
> [Severity: Medium]
> Is it intended to disable the GPU zap shader in this overlay without
> mentioning it in the commit message?
>
> The commit message only describes adding remoteproc SMMU mappings. While
> disabling the zap shader might be necessary for EL2 boot, this hardware
> feature disablement is currently an undocumented side effect.

Zap shader is not required in EL2, as Linux can perform GPU zap sequence 
on its own. Disabling it is intentional.

Thanks
Komal