linux-kernel - Re: [PATCH v4 3/5] arm64: dts: allwinner: h6: Add GPU OPP table

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Date:   Tue, 06 Sep 2022 21:10:40 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Chen-Yu Tsai <wens@...e.org>, Samuel Holland <samuel@...lland.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Clément Péron <peron.clem@...il.com>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Clément Péron <peron.clem@...il.com>
Subject: Re: [PATCH v4 3/5] arm64: dts: allwinner: h6: Add GPU OPP table

Dne torek, 06. september 2022 ob 17:30:32 CEST je Clément Péron napisal(a):
> Add an Operating Performance Points table for the GPU to
> enable Dynamic Voltage & Frequency Scaling on the H6.
> 
> The voltage range is set with minimal voltage set to the target
> and the maximal voltage set to 1.2V. This allow DVFS framework to
> work properly on board with fixed regulator.
> 
> Signed-off-by: Clément Péron <peron.clem@...il.com>
> ---
>  .../boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi | 87 +++++++++++++++++++
>  1 file changed, 87 insertions(+)
>  create mode 100644 arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi
> 
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi
> b/arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi new file mode 100644
> index 000000000000..b48049c4fc85
> --- /dev/null
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi
> @@ -0,0 +1,87 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +// Copyright (C) 2022 Clément Péron <peron.clem@...il.com>
> +
> +/ {
> +	gpu_opp_table: opp-table-gpu {
> +		compatible = "operating-points-v2";
> +
> +		opp-216000000 {
> +			opp-hz = /bits/ 64 <216000000>;
> +			opp-microvolt = <810000 810000 1200000>;
> +		};
> +
> +		opp-264000000 {
> +			opp-hz = /bits/ 64 <264000000>;
> +			opp-microvolt = <810000 810000 1200000>;
> +		};

As mentioned in clock patch review, rates below 288 MHz are deemed unstable on 
GPU PLL by vendor GPU kernel driver. At least in the BSP version that I have. 
Did you test these points? If not, better to drop them.

Best regards,
Jernej

> +
> +		opp-312000000 {
> +			opp-hz = /bits/ 64 <312000000>;
> +			opp-microvolt = <810000 810000 1200000>;
> +		};
> +
> +		opp-336000000 {
> +			opp-hz = /bits/ 64 <336000000>;
> +			opp-microvolt = <810000 810000 1200000>;
> +		};
> +
> +		opp-360000000 {
> +			opp-hz = /bits/ 64 <360000000>;
> +			opp-microvolt = <820000 820000 1200000>;
> +		};
> +
> +		opp-384000000 {
> +			opp-hz = /bits/ 64 <384000000>;
> +			opp-microvolt = <830000 830000 1200000>;
> +		};
> +
> +		opp-408000000 {
> +			opp-hz = /bits/ 64 <408000000>;
> +			opp-microvolt = <840000 840000 1200000>;
> +		};
> +
> +		opp-420000000 {
> +			opp-hz = /bits/ 64 <420000000>;
> +			opp-microvolt = <850000 850000 1200000>;
> +		};
> +
> +		opp-432000000 {
> +			opp-hz = /bits/ 64 <432000000>;
> +			opp-microvolt = <860000 860000 1200000>;
> +		};
> +
> +		opp-456000000 {
> +			opp-hz = /bits/ 64 <456000000>;
> +			opp-microvolt = <870000 870000 1200000>;
> +		};
> +
> +		opp-504000000 {
> +			opp-hz = /bits/ 64 <504000000>;
> +			opp-microvolt = <890000 890000 1200000>;
> +		};
> +
> +		opp-540000000 {
> +			opp-hz = /bits/ 64 <540000000>;
> +			opp-microvolt = <910000 910000 1200000>;
> +		};
> +
> +		opp-576000000 {
> +			opp-hz = /bits/ 64 <576000000>;
> +			opp-microvolt = <930000 930000 1200000>;
> +		};
> +
> +		opp-624000000 {
> +			opp-hz = /bits/ 64 <624000000>;
> +			opp-microvolt = <950000 950000 1200000>;
> +		};
> +
> +		opp-756000000 {
> +			opp-hz = /bits/ 64 <756000000>;
> +			opp-microvolt = <1040000 1040000 1200000>;
> +		};
> +	};
> +};
> +
> +&gpu {
> +	operating-points-v2 = <&gpu_opp_table>;
> +};
> --
> 2.34.1