Re: [PATCH] arm64: dts: qcom: monaco-arduino-monza: Add Waveshare 8" DSI touch overlay

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential
issues to consider:
- [High] arm64: dts: qcom: monaco-arduino-monza-waveshare: wrong
  mdss_dsi0 vdda-supply
- [High] arm64: dts: qcom: Makefile: monaco-el2.dtbo applied to non-EL2
  Waveshare DTB
--

commit b8a3c8f8c7e536ea10afaadd72a3ac9f01d55e3c
Author: Vishnu Saini <vishnu.saini@oss.qualcomm.com>

arm64: dts: qcom: monaco-arduino-monza: Add Waveshare 8" DSI touch overlay

This commit adds a device tree overlay for the Waveshare 8" DSI TOUCH-A
panel and touch controller on the Arduino Monza board, disabling the
shared DSI0 HDMI bridge path when applied.

> diff --git a/arch/arm64/boot/dts/qcom/Makefile b/arch/arm64/boot/dts/qcom/Makefile
> index 8329c06b60a3f..faa0e0f7b867f 100644
> --- a/arch/arm64/boot/dts/qcom/Makefile
> +++ b/arch/arm64/boot/dts/qcom/Makefile
> @@ -83,6 +83,11 @@ dtb-$(CONFIG_ARCH_QCOM)	+= monaco-arduino-monza.dtb
>  monaco-arduino-monza-el2-dtbs	:= monaco-arduino-monza.dtb monaco-el2.dtbo
>  
>  dtb-$(CONFIG_ARCH_QCOM)	+= monaco-arduino-monza-el2.dtb
> +
> +monaco-arduino-monza-waveshare-8-dsi-touch-a-dtbs	:= monaco-arduino-monza.dtb monaco-el2.dtbo monaco-arduino-monza-waveshare-8-dsi-touch-a.dtbo

[Severity: High]
Should monaco-arduino-monza-waveshare-8-dsi-touch-a-dtbs omit
monaco-el2.dtbo?  Including monaco-el2.dtbo in the non-EL2 target disables
gpu_zap_shader and iris, and attaches EL2-only apps_smmu IOMMU mappings to
remoteproc_adsp, remoteproc_cdsp, and remoteproc_gpdsp when booting in the
default EL1 mode under Gunyah.

> diff --git a/arch/arm64/boot/dts/qcom/monaco-arduino-monza-waveshare-8-dsi-touch-a.dtso b/arch/arm64/boot/dts/qcom/monaco-arduino-monza-waveshare-8-dsi-touch-a.dtso
> new file mode 100644
> index 0000000000000..003c5bcea4973
> --- /dev/null
> +++ b/arch/arm64/boot/dts/qcom/monaco-arduino-monza-waveshare-8-dsi-touch-a.dtso

[ ... ]

> +&mdss_dsi0 {
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	vdda-supply = <&vreg_l1c>;
> +
> +	panel@0 {
> +		compatible = "waveshare,8.0-dsi-touch-a", "jadard,jd9365da-h3";
> +		reg = <0>;
> +		backlight = <&wsgpio>;
> +		reset-gpios = <&wsgpio 1 GPIO_ACTIVE_LOW>;
> +		vccio-supply = <&panel_iovcc>;
> +		vdd-supply = <&panel_avdd>;
> +
> +		port {
> +			panel_in: endpoint {
> +				remote-endpoint = <&mdss_dsi0_out>;
> +			};
> +		};
> +	};
> +};
> +
> +&mdss_dsi0_out {
> +	data-lanes = <0 1 2 3>;
> +	remote-endpoint = <&panel_in>;
> +};
> +
> +&mdss_dsi0_phy {
> +	vdds-supply = <&vreg_l4a>;
> +};

[Severity: High]
Does setting vdda-supply = <&vreg_l1c> on mdss_dsi0 overwrite the SoM's
1.2V DSI supply with the LPDDR VDDQ regulator?

In arch/arm64/boot/dts/qcom/monaco-monza-som.dtsi, mdss_dsi0 already uses
vreg_l5a (1.2V), while vreg_l1c is the 0.3V-0.512V LPDDR VDDQ rail:

arch/arm64/boot/dts/qcom/monaco-monza-som.dtsi:
		vreg_l1c: ldo1 { /* LPDDR VDDQ */
			regulator-name = "vreg_l1c";
			regulator-min-microvolt = <300000>;
			regulator-max-microvolt = <512000>;
    ...
&mdss_dsi0 {
	vdda-supply = <&vreg_l5a>;
};

&mdss_dsi0_phy {
	vdds-supply = <&vreg_l4a>;
};

Overriding vdda-supply with vreg_l1c leaves vreg_l5a unvoted and causes
the DSI driver to disable the LPDDR VDDQ regulator on display suspend or
probe unwind.  Both vdda-supply on mdss_dsi0 and the redundant
mdss_dsi0_phy node can be dropped from the overlay since
monaco-monza-som.dtsi already configures them.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261114-monza_waveshare_dtso-v1-1-4b7c80e90e08@oss.qualcomm.com?part=1