linux-kernel - Re: [PATCH] arm64: dts: ti: k3-am62l: support cpufreq

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Message-ID: <77815f93-e5cc-407b-8e09-93b007f3ecc9@ti.com>
Date: Thu, 22 Jan 2026 08:36:45 -0600
From: Kendall Willis <k-willis@...com>
To: Dhruva Gole <d-gole@...com>, Nishanth Menon <nm@...com>, "Vignesh
 Raghavendra" <vigneshr@...com>, Tero Kristo <kristo@...nel.org>, Rob Herring
	<robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
	<conor+dt@...nel.org>
CC: <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Bryan Brattlof <bb@...com>, Viresh Kumar
	<viresh.kumar@...aro.org>
Subject: Re: [PATCH] arm64: dts: ti: k3-am62l: support cpufreq

On 1/22/26 04:49, Dhruva Gole wrote:
> Enable CPUFreq support for AM62L SoC by adding the relevant OPP efuse table
> syscon to k3-am62l-wakeup.dtsi for speed grade detection.
> 
> Add the operating-points-v2 table with CPU frequency steps from 200MHz to
> 1.25GHz to k3-am62l3.dtsi
> 
> Configure CPU clocks to reference the SCMI clock controller for frequency
> scaling
> 
> This enables proper CPU frequency scaling capabilities for the AM62L SoC
> using the ARM SCMI protocol to interact with the power management firmware.
> 
> Signed-off-by: Dhruva Gole <d-gole@...com>
> ---
> The driver changes were merged previously [0], and so the DT patch
> is now being posted seperately.
> 
> Logs:
> 
> root@...2lxx-evm:~# cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_frequencies
> 200000 400000 600000 800000 1000000 1250000
> 200000 400000 600000 800000 1000000 1250000
> 
> Changelog:
> - fix the bit fiels in the OPPs as per Kendall's suggestion
> - Fix the scmi_clk ID of the second A53 core
> 
> [1] https://lore.kernel.org/all/20260120-am62l-cpufreq-v3-0-8c69b80168a3@ti.com/
> ---
>   arch/arm64/boot/dts/ti/k3-am62l-wakeup.dtsi |  5 +++
>   arch/arm64/boot/dts/ti/k3-am62l3.dtsi       | 47 +++++++++++++++++++++++++++++
>   2 files changed, 52 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-am62l-wakeup.dtsi b/arch/arm64/boot/dts/ti/k3-am62l-wakeup.dtsi
> index 61bfcdcfc66ea8d802a36ed43cd01fbbf3decc70..a42ccd0d2fcc4d204cae81508f839c44ce83f558 100644
> --- a/arch/arm64/boot/dts/ti/k3-am62l-wakeup.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-am62l-wakeup.dtsi
> @@ -127,6 +127,11 @@ chipid: chipid@14 {
>   			bootph-all;
>   		};
>   
> +		opp_efuse_table: syscon@18 {
> +			compatible = "ti,am62-opp-efuse-table", "syscon";
> +			reg = <0x18 0x4>;
> +		};
> +
>   		cpsw_mac_syscon: ethernet-mac-syscon@...0 {
>   			compatible = "ti,am62p-cpsw-mac-efuse", "syscon";
>   			reg = <0x2000 0x8>;
> diff --git a/arch/arm64/boot/dts/ti/k3-am62l3.dtsi b/arch/arm64/boot/dts/ti/k3-am62l3.dtsi
> index da220b85151227c63f59b2b8ec48ae2ebb37e7bf..26d3040ff53259daba21b39a55bb8a2ed65d4e8f 100644
> --- a/arch/arm64/boot/dts/ti/k3-am62l3.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-am62l3.dtsi
> @@ -39,6 +39,8 @@ cpu0: cpu@0 {
>   			d-cache-line-size = <64>;
>   			d-cache-sets = <128>;
>   			next-level-cache = <&l2_0>;
> +			operating-points-v2 = <&a53_opp_table>;
> +			clocks = <&scmi_clk 356>;
>   		};
>   
>   		cpu1: cpu@1 {
> @@ -53,6 +55,8 @@ cpu1: cpu@1 {
>   			d-cache-line-size = <64>;
>   			d-cache-sets = <128>;
>   			next-level-cache = <&l2_0>;
> +			operating-points-v2 = <&a53_opp_table>;
> +			clocks = <&scmi_clk 357>;
>   		};
>   	};
>   
> @@ -64,4 +68,47 @@ l2_0: l2-cache0 {
>   		cache-line-size = <64>;
>   		cache-sets = <256>;
>   	};
> +
> +	a53_opp_table: opp-table {
> +		compatible = "operating-points-v2-ti-cpu";
> +		opp-shared;
> +		syscon = <&opp_efuse_table>;
> +
> +		opp-200000000 {
> +			opp-hz = /bits/ 64 <200000000>;
> +			opp-supported-hw = <0x01 0x0003>;
> +			clock-latency-ns = <6000000>;
> +		};
> +
> +		opp-400000000 {
> +			opp-hz = /bits/ 64 <400000000>;
> +			opp-supported-hw = <0x01 0x0003>;
> +			clock-latency-ns = <6000000>;
> +		};
> +
> +		opp-600000000 {
> +			opp-hz = /bits/ 64 <600000000>;
> +			opp-supported-hw = <0x01 0x0003>;
> +			clock-latency-ns = <6000000>;
> +		};
> +
> +		opp-800000000 {
> +			opp-hz = /bits/ 64 <800000000>;
> +			opp-supported-hw = <0x01 0x0003>;
> +			clock-latency-ns = <6000000>;
> +		};
> +
> +		opp-1000000000 {
> +			opp-hz = /bits/ 64 <1000000000>;
> +			opp-supported-hw = <0x01 0x0003>;
> +			clock-latency-ns = <6000000>;
> +		};

Thanks for implementing the feedback! One last thing is I think 
opp-1000000000 should have the opp-supported-hw value of 0x02 because 
speed grade E only supports up to 833 MHz.

> +
> +		opp-1250000000 {
> +			opp-hz = /bits/ 64 <1250000000>;
> +			opp-supported-hw = <0x01 0x0002>;
> +			clock-latency-ns = <6000000>;
> +			opp-suspend;
> +		};
> +	};
>   };
> 
> ---
> base-commit: e3b32dcb9f23e3c3927ef3eec6a5842a988fb574
> change-id: 20260122-am62l-dt-cpufreq-c24f0236ad15
> 
> Best regards,

Best,
Kendall Willis <k-willis@...com>