Re: [PATCH v3 2/2] arm64: dts: qcom: purwa: Add PSCI SYSTEM_RESET2 types

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `reboot-mode` child node in the `psci` node violates the DT binding schema and is completely unhandled by the kernel, resulting in validation failures and a non-functional feature.
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commit 6aadf5c7e368cd8a19850d3a52be3816bc1f1974
Author: Xin Liu <xin.liu@oss.qualcomm.com>

arm64: dts: qcom: purwa: Add PSCI SYSTEM_RESET2 types

This commit adds vendor-specific reset types to the psci device tree node
as reboot-modes for the purwa-iot-evk. The new modes are intended to allow
the device to reboot into fastboot or emergency download mode.

> diff --git a/arch/arm64/boot/dts/qcom/purwa-iot-evk.dts b/arch/arm64/boot/dts/qcom/purwa-iot-evk.dts
> --- a/arch/arm64/boot/dts/qcom/purwa-iot-evk.dts
> +++ b/arch/arm64/boot/dts/qcom/purwa-iot-evk.dts
[ ... ]
> @@ -1180,6 +1180,13 @@ &pmk8550_pwm {
>  	status = "okay";
>  };
>  
> +&psci {
> +	reboot-mode {
> +		mode-bootloader = <0x80010001 0x2>;
> +		mode-edl = <0x80000000 0x1>;
> +	};
> +};

[Severity: Medium]
Will this reboot-mode node cause a dtbs_check validation error?

The psci device tree binding schema in 
Documentation/devicetree/bindings/arm/psci.yaml specifies
"additionalProperties: false" and does not define a reboot-mode child node.
Furthermore, this node lacks a compatible string, which means standard
reboot-mode drivers will not bind to it.

Additionally, are these vendor-specific reset modes actually supported by the
psci driver?

Looking at psci_sys_reset() in drivers/firmware/psci/psci.c, the kernel
hardcodes the arguments for SYSTEM_RESET2 to 0 instead of parsing them
from the device tree:

psci_sys_reset() {
		/*
		 * reset_type[31] = 0 (architectural)
		 * reset_type[30:0] = 0 (SYSTEM_WARM_RESET)
		 * cookie = 0 (ignored by the implementation)
		 */
		invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0);
}

This means that executing a command like "reboot edl" might just perform
a standard warm reset rather than the requested vendor reset, leaving the
feature non-functional.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260901075552.3558150-1-xin.liu@oss.qualcomm.com?part=2