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References: <20230221153740.1620529-1-angelogioacchino.delregno@collabora.com> <20230221153740.1620529-11-angelogioacchino.delregno@collabora.com>
In-Reply-To: <20230221153740.1620529-11-angelogioacchino.delregno@collabora.com>
From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Wed, 22 Feb 2023 15:06:53 +0800
Message-ID: <CAGXv+5FqZPXaE8tyEFtejsYpKMLzUt5R_QnkbQrDSBM_u7rRYg@mail.gmail.com>
Subject: Re: [PATCH v2 10/10] drm/panfrost: Add new compatible for Mali on the
 MT8183 SoC
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Cc:     airlied@gmail.com, daniel@ffwll.ch, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, steven.price@arm.com,
        alyssa.rosenzweig@collabora.com, matthias.bgg@gmail.com,
        robh@kernel.org, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
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On Tue, Feb 21, 2023 at 11:37 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.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@collabora.com>
> Reviewed-by: Steven Price <steven.price@arm.com>

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