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Date:   Tue, 25 Apr 2023 18:10:28 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Roman Beranek <me@crly.cz>
Cc:     Chen-Yu Tsai <wens@csie.org>, David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Samuel Holland <samuel@sholland.org>,
        Frank Oltmanns <frank@oltmanns.dev>,
        Icenowy Zheng <icenowy@aosp.io>, Ondrej Jirman <megi@xff.cz>,
        dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/7] arm64: dts: allwinner: a64: assign PLL_MIPI to
 CLK_TCON0
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 <20230418074008.69752-5-me@crly.cz>
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On Tue, Apr 18, 2023 at 09:40:05AM +0200, Roman Beranek wrote:
> Assign pll-mipi parent to tcon0's source clock via 'assigned-clocks'.
>=20
> Signed-off-by: Roman Beranek <me@crly.cz>
> ---
>  arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 2 ++
>  1 file changed, 2 insertions(+)
>=20
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi b/arch/arm64/b=
oot/dts/allwinner/sun50i-a64.dtsi
> index 62f45f71ec65..e6a194db420d 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> @@ -411,6 +411,8 @@ tcon0: lcd-controller@1c0c000 {
>  			#clock-cells =3D <0>;
>  			resets =3D <&ccu RST_BUS_TCON0>, <&ccu RST_BUS_LVDS>;
>  			reset-names =3D "lcd", "lvds";
> +			assigned-clocks =3D <&ccu CLK_TCON0>;
> +			assigned-clock-parents =3D <&ccu CLK_PLL_MIPI>;

assigned-clock-parents is fairly fragile, and it's essentially an OS
decision, so that doesn't have much to do with the platform.

Just force the parent in the clock driver, and prevent it from being
reparented. It will be more robust, and we will be able to change it in
the future easily.

Maxime

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