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From:   Alexandre Mergnat <amergnat@baylibre.com>
Date:   Wed, 15 Mar 2023 10:26:23 +0100
Message-ID: <CAFGrd9qVhJb--COXJmGHuW6NxDnXZGdQnxbHGRvaA5Jqhx-yNg@mail.gmail.com>
Subject: Re: [PATCH 07/21] dt-bindings: display: mediatek: dpi: add binding
 for MT8365
To:     Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc:     Daniel Vetter <daniel@ffwll.ch>, CK Hu <ck.hu@mediatek.com>,
        Jitao Shi <jitao.shi@mediatek.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Sam Ravnborg <sam@ravnborg.org>,
        Rob Herring <robh+dt@kernel.org>,
        =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Xinlei Lee <xinlei.lee@mediatek.com>,
        Guillaume La Roque <glaroque@baylibre.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        dri-devel@lists.freedesktop.org,
        Fabien Parent <fparent@baylibre.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Hi Chun-Kuang,

Le lun. 13 mars 2023 =C3=A0 16:17, Chun-Kuang Hu <chunkuang.hu@kernel.org> =
a =C3=A9crit :
>
> Hi, Alexandre:
>
> Alexandre Mergnat <amergnat@baylibre.com> =E6=96=BC 2023=E5=B9=B43=E6=9C=
=889=E6=97=A5 =E9=80=B1=E5=9B=9B =E4=B8=8B=E5=8D=8810:23=E5=AF=AB=E9=81=93=
=EF=BC=9A
> >
> > From: Fabien Parent <fparent@baylibre.com>
> >
> > DPI for MT8365 is compatible with MT8192 but requires an additional
> > clock. Modify the documentation to requires this clock only on MT8365 S=
oCs.
>
> If MT8365 DPI has additional clock, why it is compatible with MT8192 DPI?
> I think some part of MT8165 DPI works under the speed control by the
> DPI clock and this is different with MT8192 DPI, how could these two
> are compatible?

AFAII, The mtk_dpi driver manage the 4th clock as optional
dpi->dpi_clk =3D devm_clk_get_optional(dev, "dpi");
And all configuration variables for mt8192 are the same for mt8365.
These configuration clock variables (like cal_factor) aren't
correlated with the 4th clock.
The clock number doesn't impact the configuration variable because the
4th clock is simply retrieved from DTS, saved in the driver structure
and prepare/unprepare/enable/disable, like other clocks.

Regards,
Alex