linux-kernel - Re: [PATCH 5/9] dt-bindings: gpu: mali-bifrost: Add a compatible for MediaTek MT8186

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Message-ID: <33ae8a64-277b-0c53-fcf3-f4eb2fccda49@collabora.com>
Date:   Thu, 9 Feb 2023 10:58:49 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     airlied@...il.com, tomeu.vizoso@...labora.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, steven.price@....com,
        robh+dt@...nel.org, linux-mediatek@...ts.infradead.org,
        alyssa.rosenzweig@...labora.com, krzysztof.kozlowski+dt@...aro.org,
        matthias.bgg@...il.com, linux-arm-kernel@...ts.infradead.org,
        Fei Shao <fshao@...omium.org>, Nick Fan <Nick.Fan@...iatek.com>
Subject: Re: [PATCH 5/9] dt-bindings: gpu: mali-bifrost: Add a compatible for
 MediaTek MT8186

Il 09/02/23 10:45, Chen-Yu Tsai ha scritto:
> On Thu, Feb 9, 2023 at 5:20 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Il 09/02/23 09:49, Chen-Yu Tsai ha scritto:
>>> On Wed, Feb 8, 2023 at 6:37 PM AngeloGioacchino Del Regno
>>> <angelogioacchino.delregno@...labora.com> wrote:
>>>>
>>>> Get GPU support on MT8186 by adding its compatible.
>>>
>>> I'd skip MT8186 for now. We have to work out some binning details for the
>>> OPP, in particular how to deal with both Panfrost (or Mali) and SVS adding
>>> the OPP table. We were just looking at the Mali driver today.
>>>
>>
>> Dealing with binning is fairly easy... I have something already done for
>> that one, but I'm not sure that it would be the best option.
>> My solution makes use of opp-supported-hw by "standard means", but perhaps
>> let's have a separated conversation about it?
>>
>> I don't think that skipping this would give any benefit though, because
>> that is only adding a compatible and whatever binning support would have
>> to be generic and 99% not bound to any mediatek specific compatible.
> 
> The binning is related to voltage range, not maximum OPP. So it's more
> like fast/slow example in Documentation/devicetree/bindings/opp/opp-v2.yaml
> or the opp/allwinner,sun50i-h6-operating-points.yaml, minus the efuse node.
> 
> The downstream DT currently looks like this:
> 
> opp-950000000 {
>          opp-hz = /bits/ 64 <950000000>;
> 
> /* This is Mali specific; ignore
>          opp-hz-real = /bits/ 64 <950000000>,
>                        /bits/ 64 <950000000>;
> */
>          opp-microvolt = <900000>, <1000000>;
>          opp-microvolt-bin4 = <875000>, <975000>;
>          opp-microvolt-bin5 = <850000>, <950000>;
> };
> 

Yes, my option is, in short:

	opp-900000000 {
		opp-hz = /bits/ 64 <900000000>;
		opp-microvolt = <850000>;
		opp-supported-hw = <0xcf>;
	};

	opp-900000000-bin4 {
		opp-hz = /bits/ 64 <900000000>;
		opp-microvolt = <837500>;
		opp-supported-hw = <0x10>;
	};

	opp-900000000-bin5 {
		opp-hz = /bits/ 64 <900000000>;
		opp-microvolt = <825000>;
		opp-supported-hw = <0x20>;
	};



> 
> ChenYu