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Message-ID: <f821e008-c984-2f60-60c0-46220cada909@kontron.de>
Date:   Tue, 6 Jun 2023 09:13:24 +0200
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Subject: Re: [PATCH V2 1/2] arm64: dts: imx8mn-beacon: Add HDMI video with
 sound
Content-Language: en-US, de-DE
To:     Adam Ford <aford173@gmail.com>,
        linux-arm-kernel@lists.infradead.org
Cc:     aford@beaconembedded.com, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Shawn Guo <shawnguo@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>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230605223323.578198-1-aford173@gmail.com>
 <20230605223323.578198-2-aford173@gmail.com>
From:   Frieder Schrempf <frieder.schrempf@kontron.de>
In-Reply-To: <20230605223323.578198-2-aford173@gmail.com>
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Hi Adam,

On 06.06.23 00:33, Adam Ford wrote:
> The Beacon Embedded imx8mn development kit has a DSI
> to HDMI bridge chip.  The bridge supports stereo audio
> and hot-plug detection.
> 
> Signed-off-by: Adam Ford <aford173@gmail.com>
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mn-beacon-kit.dts b/arch/arm64/boot/dts/freescale/imx8mn-beacon-kit.dts
> index 1392ce02587b..2108ec8c019c 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mn-beacon-kit.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mn-beacon-kit.dts

I have to minor comments below, otherwise this looks good to me.

As I'm trying to come up with similar changes for our boards I also have
some questions below. Maybe you could share your knowledge on these.

Thanks!
Frieder

> @@ -16,4 +16,138 @@ / {
>  	chosen {
>  		stdout-path = &uart2;
>  	};
> +
> +	connector {
> +		compatible = "hdmi-connector";
> +		type = "a";
> +
> +		port {
> +			hdmi_connector_in: endpoint {
> +				remote-endpoint = <&adv7535_out>;
> +			};
> +		};
> +	};
> +
> +	reg_hdmi: regulator-hdmi-dvdd {
> +		compatible = "regulator-fixed";
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_reg_hdmi>;
> +		regulator-name = "hdmi_pwr_en";
> +		regulator-min-microvolt = <3300000>;
> +		regulator-max-microvolt = <3300000>;
> +		gpio = <&gpio2 11 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +		startup-delay-us = <70000>;
> +		regulator-always-on;
> +	};
> +
> +	sound-hdmi {
> +		compatible = "simple-audio-card";
> +		simple-audio-card,name = "sound-hdmi";
> +		simple-audio-card,format = "i2s";
> +
> +		simple-audio-card,cpu {
> +			sound-dai = <&sai5 0>;
> +			system-clock-direction-out;
> +		};
> +
> +		simple-audio-card,codec {
> +			sound-dai = <&adv_bridge>;
> +		};
> +	};
> +};
> +
> +&i2c2 {
> +	adv_bridge: hdmi@3d {
> +		compatible = "adi,adv7535";
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_hdmi_bridge>;
> +		reg = <0x3d>, <0x3b>;
> +		reg-names = "main", "cec";
> +		adi,dsi-lanes = <4>;

On our boards we have this working with 4 lanes. But we also have some
boards that only have 2 DSI lanes connected. We don't get any image in
on the display in this case. Did you ever try 2 lanes or do you have an
idea what could be wrong?

> +		adi,fixed-lanes;

I think this property comes from downstream and should be removed. I
don't see it anywhere in the upstream driver or bindings.

> +		dvdd-supply = <&reg_hdmi>;
> +		v3p3-supply = <&reg_hdmi>;
> +		v1p2-supply = <&reg_hdmi>;
> +		a2vdd-supply = <&reg_hdmi>;
> +		avdd-supply = <&reg_hdmi>;
> +		pvdd-supply = <&reg_hdmi>;

Please sort the reg properties above alphabetically.

> +		interrupt-parent = <&gpio1>;
> +		interrupts = <9 IRQ_TYPE_LEVEL_LOW>;
> +		#sound-dai-cells = <0>;
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;
> +
> +				adv7535_in: endpoint {
> +					remote-endpoint = <&dsi_out>;
> +				};
> +			};
> +
> +			port@1 {
> +				reg = <1>;
> +
> +				adv7535_out: endpoint {
> +					remote-endpoint = <&hdmi_connector_in>;
> +				};
> +			};
> +		};
> +	};
> +};
> +
> +&lcdif {
> +	assigned-clocks = <&clk IMX8MN_VIDEO_PLL1>;
> +	assigned-clock-rates = <594000000>;

Just out of interest: Why do you need to set the video PLL clock here
and how did you determine the "correct" value? Why is this missing in
the i.MX8MM dts?

> +	status = "okay";
> +};
> +
> +&mipi_dsi {
> +	samsung,esc-clock-frequency = <20000000>;

Same here, I'm interested in how you determined the "correct" value for
this property. Are there any rules to follow?

> +	status = "okay";
> +
> +	ports {
> +		port@1 {
> +			reg = <1>;
> +
> +			dsi_out: endpoint {
> +				remote-endpoint = <&adv7535_in>;
> +			};
> +		};
> +	};
> +};
> +
> +&sai5 {
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&pinctrl_sai5>;
> +	assigned-clocks = <&clk IMX8MN_CLK_SAI5>;
> +	assigned-clock-parents = <&clk IMX8MN_AUDIO_PLL1_OUT>;
> +	assigned-clock-rates = <24576000>;
> +	#sound-dai-cells = <0>;
> +	status = "okay";
> +};
> +
> +&iomuxc {
> +	pinctrl_hdmi_bridge: hdmibridgegrp {
> +		fsl,pins = <
> +			MX8MN_IOMUXC_GPIO1_IO09_GPIO1_IO9		0x19
> +		>;
> +	};
> +
> +	pinctrl_reg_hdmi: reghdmigrp {
> +		fsl,pins = <
> +			MX8MN_IOMUXC_SD1_STROBE_GPIO2_IO11              0x16
> +		>;
> +	};
> +
> +	pinctrl_sai5: sai5grp {
> +		fsl,pins = <
> +			MX8MN_IOMUXC_SAI5_RXD3_SAI5_TX_DATA0	0xd6
> +			MX8MN_IOMUXC_SAI5_RXD2_SAI5_TX_BCLK	0xd6
> +			MX8MN_IOMUXC_SAI5_RXD1_SAI5_TX_SYNC	0xd6
> +		>;
> +	};
>  };