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

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Message-ID: <CAGXv+5EhDGuzoBA9ZV2=3PVZ209eFq+wOOcTGVvG+gmOnf5txQ@mail.gmail.com>
Date:   Thu, 9 Feb 2023 17:45:22 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
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

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>;
};


ChenYu