Re: [PATCH v1 07/12] arm64: dts: imx8mp-var-som-symphony: add HDMI support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] The `lcdif3` display controller is not enabled, breaking the HDMI video pipeline because it is the sole video source for the HDMI interface on the i.MX8MP.
- [High] The `hdmi_tx` node lacks pin multiplexing configuration for the DDC and HPD pins, which breaks EDID reading and Hot Plug Detect.
--

commit aea2bfe7fe7a358c3badcef46d4148e23cb37818
Author: Stefano Radaelli <stefano.r@variscite.com>

arm64: dts: imx8mp-var-som-symphony: add HDMI support

Enable HDMI output on Symphony iMX8MP Carrier Board along with audio
support.

> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-var-som-symphony.dts b/arch/arm64/boot/dts/freescale/imx8mp-var-som-symphony.dts
> index fe16996494141..6878b89c4db8e 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp-var-som-symphony.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mp-var-som-symphony.dts

[ ... ]

> @@ -74,6 +86,41 @@ reg_usdhc2_vqmmc: regulator-usdhc2-vqmmc {
>  		states = <3300000 0x0 1800000 0x1>;
>  		vin-supply = <&ldo5>;
>  	};
> +
> +	sound-hdmi {
> +		compatible = "fsl,imx-audio-hdmi";
> +		model = "audio-hdmi";
> +		audio-cpu = <&aud2htx>;
> +		hdmi-out;
> +	};
> +};
> +
> +&aud2htx {
> +	status = "okay";
> +};
> +
> +&hdmi_pai {
> +	status = "okay";
> +};
> +
> +&hdmi_pvi {
> +	status = "okay";
> +};
> +

[Severity: High]
Does the lcdif3 display controller also need to be enabled here?

On the i.MX8MP architecture, the HDMI transmitter receives its video stream
from the Parallel Video Interface (hdmi_pvi), which is driven exclusively by
the lcdif3 display controller.

Since lcdif3 is disabled in the base imx8mp.dtsi, omitting its enablement
means the DRM framework will lack a CRTC for the HDMI pipeline, causing video
output initialization to fail.

> +&hdmi_tx {
> +	status = "okay";
> +

[Severity: High]
Does this node need explicit pin multiplexing configuration for the DDC and
HPD pins?

Without pinctrl-names and pinctrl-0 properties here, the configuration relies
on the bootloader. If the kernel does not configure the internal pull-ups for
the I2C DDC bus and route the pins correctly, Hot Plug Detect and EDID reads
will fail, preventing the driver from detecting display capabilities.

> +	ports {
> +		port@1 {
> +			hdmi_tx_out: endpoint {
> +				remote-endpoint = <&hdmi_in>;
> +			};
> +		};
> +	};
> +};
> +
> +&hdmi_tx_phy {
> +	status = "okay";
>  };
>  
>  &i2c3 {

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1780487415.git.stefano.r@variscite.com?part=7