Re: [PATCH v7 3/6] arm64: dts: qcom: sc8280xp: Add Iris core

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The `iris` device tree node adds an `mmcx` power domain and two `required-opps` per OPP entry, which violates the fallback compatible's DT binding schema and causes hardware instability due to unhandled power domain scaling.
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commit 39fd9222ebc24cef337abe30cd891e4af77696e1
Author: Konrad Dybcio <konradybcio@kernel.org>

arm64: dts: qcom: sc8280xp: Add Iris core

Add the required nodes to enable Iris core on SC8280XP.

> diff --git a/arch/arm64/boot/dts/qcom/sc8280xp.dtsi b/arch/arm64/boot/dts/qcom/sc8280xp.dtsi
> index 41c57e7dc4333..45e1dd5a230cd 100644
> --- a/arch/arm64/boot/dts/qcom/sc8280xp.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc8280xp.dtsi
[ ... ]
> @@ -4181,6 +4189,97 @@ usb_1_dwc3_ss: endpoint {
>  			};
>  		};
>  
> +		iris: video-codec@aa00000 {
> +			compatible = "qcom,sc8280xp-iris", "qcom,sm8250-venus";
> +			reg = <0x0 0x0aa00000 0x0 0x100000>;
> +			interrupts = <GIC_SPI 174 IRQ_TYPE_LEVEL_HIGH>;
[ ... ]
> +			power-domains = <&videocc MVS0C_GDSC>,
> +					<&videocc MVS0_GDSC>,
> +					<&rpmhpd SC8280XP_MX>,
> +					<&rpmhpd SC8280XP_MMCX>;
> +			power-domain-names = "venus",
> +					     "vcodec0",
> +					     "mx",
> +					     "mmcx";

The qcom,sm8250-venus fallback compatible is used here. Does the
qcom,sm8250-venus.yaml device tree binding schema support a fourth power
domain?

It appears the schema might restrict power-domains to a maximum of 3 items
(venus, vcodec0, mx), which could trigger dtbs_check failures when mmcx
is added.

[ ... ]
> +			iris_opp_table: opp-table {
> +				compatible = "operating-points-v2";
> +
> +				opp-240000000 {
> +					opp-hz = /bits/ 64 <240000000>;
> +					required-opps = <&rpmhpd_opp_svs>,
> +							<&rpmhpd_opp_low_svs>;
> +				};
[ ... ]
> +				opp-560000000 {
> +					opp-hz = /bits/ 64 <560000000>;
> +					required-opps = <&rpmhpd_opp_nom>,
> +							<&rpmhpd_opp_turbo_l1>;
> +				};
> +			};
> +		};

When using the qcom,sm8250-venus fallback, the Venus driver currently
configures a single OPP PM domain (mx) via dev_pm_opp_set_config().

Since this node specifies two required-opps per state, will the generic OPP
core skip scaling the mmcx rail? When _set_required_opps() in
drivers/opp/core.c iterates over expected devices, a missing mmcx device
pointer might cause the mmcx rail to remain trapped at the static low_svs
level voted by the videocc node.

If the Venus hardware operates at turbo frequencies (e.g., 560MHz) while mmcx
remains at low_svs, can this undervolt the hardware and cause system
instability?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260515-iris-sc8280xp-v7-0-2e21f6db1897@oss.qualcomm.com?part=3