Re: [PATCH] arm64: dts: imx8mq: Add clock parents for mipi dphy

From: Shawn Guo <shawnguo@kernel.org>
To: "Guido Günther" <agx@sigxcpu.org>
Cc: Rob Herring <robh+dt@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>, Peng Fan <peng.fan@nxp.com>,
	Dong Aisheng <aisheng.dong@nxp.com>,
	Anson Huang <Anson.Huang@nxp.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Shengjiu Wang <shengjiu.wang@nxp.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: imx8mq: Add clock parents for mipi dphy
Date: Sun, 10 Jan 2021 20:46:29 +0800	[thread overview]
Message-ID: <20210110124629.GO28365@dragon> (raw)
In-Reply-To: <dd135fa55084d886bd6daf777d76677f232c53c6.1608313793.git.agx@sigxcpu.org>

On Fri, Dec 18, 2020 at 06:50:05PM +0100, Guido Günther wrote:
> This makes sure the clock tree setup for the dphy is not dependent on
> other components.
> 
> Without this change bringing up the display can fail like
> 
>   kernel: phy phy-30a00300.dphy.2: Invalid CM/CN/CO values: 165/217/1
>   kernel: phy phy-30a00300.dphy.2: for hs_clk/ref_clk=451656000/593999998 ~ 165/217
> 
> if LCDIF doesn't set up that part of the clock tree first. This was
> noticed when testing the Librem 5 devkit with defconfig. It doesn't
> happen when modules are built in.
> 
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> ---
>  arch/arm64/boot/dts/freescale/imx8mq.dtsi | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mq.dtsi b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> index a841a023e8e0..ca0847e8f13c 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
> @@ -1016,9 +1016,14 @@ dphy: dphy@30a00300 {
>  				reg = <0x30a00300 0x100>;
>  				clocks = <&clk IMX8MQ_CLK_DSI_PHY_REF>;
>  				clock-names = "phy_ref";
> -				assigned-clocks = <&clk IMX8MQ_CLK_DSI_PHY_REF>;
> -				assigned-clock-parents = <&clk IMX8MQ_VIDEO_PLL1_OUT>;
> -				assigned-clock-rates = <24000000>;
> +				assigned-clocks = <&clk IMX8MQ_VIDEO_PLL1_REF_SEL>,
> +						  <&clk IMX8MQ_VIDEO_PLL1_BYPASS>,
> +						  <&clk IMX8MQ_CLK_DSI_PHY_REF>,
> +						  <&clk IMX8MQ_VIDEO_PLL1>;

You do not seem to set parent or rate on IMX8MQ_VIDEO_PLL1.  Why do you
have it here?

Shawn

> +				assigned-clock-parents = <&clk IMX8MQ_CLK_25M>,
> +						  <&clk IMX8MQ_VIDEO_PLL1>,
> +						  <&clk IMX8MQ_VIDEO_PLL1_OUT>;
> +				assigned-clock-rates = <0>, <0>, <24000000>;
>  				#phy-cells = <0>;
>  				power-domains = <&pgc_mipi>;
>  				status = "disabled";
> -- 
> 2.29.2
> 