linux-kernel - Re: [PATCH v3 10/11] drm/panfrost: Add new compatible for Mali on the MT8183 SoC

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Message-ID: <CAGXv+5Ekx0NNf349qYsJXXXpNSFnT6Qq1zved9peBpn1ybVfKA@mail.gmail.com>
Date:   Fri, 24 Feb 2023 18:03:50 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     airlied@...il.com, daniel@...ll.ch, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, steven.price@....com,
        alyssa.rosenzweig@...labora.com, matthias.bgg@...il.com,
        robh@...nel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v3 10/11] drm/panfrost: Add new compatible for Mali on the
 MT8183 SoC

On Thu, Feb 23, 2023 at 9:35 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> The "mediatek,mt8183-mali" compatible uses platform data that calls for
> getting (and managing) two regulators ("mali" and "sram") but devfreq
> does not support this usecase, resulting in DVFS not working.
>
> Since a lot of MediaTek SoCs need to set the voltages for the GPU SRAM
> regulator in a specific relation to the GPU VCORE regulator, a MediaTek
> SoC specific driver was introduced to automatically satisfy, through
> coupling, these constraints: this means that there is at all no need to
> manage both regulators in panfrost but to otherwise just manage the main
> "mali" (-> gpu vcore) regulator instead.
>
> Keeping in mind that we cannot break the ABI, the most sensible route
> (avoiding hacks and uselessly overcomplicated code) to get a MT8183
> node with one power supply was to add a new "mediatek,mt8183b-mali"
> compatible, which effectively deprecates the former.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> Reviewed-by: Steven Price <steven.price@....com>

Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>