Re: [PATCH v5 3/4] arm64: dts: qcom: shikra-cqm-evk: Enable display and add ili7807s panel

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] drm/panel: ilitek-ili7807s: unused wled-supply leaves display dark
--

commit 826d42f8e3c3f2865af6f33ebaf53a4c3f08d32f
Author: Arpit Saini <arpit.saini@oss.qualcomm.com>

arm64: dts: qcom: shikra-cqm-evk: Enable display and add ili7807s panel

Enable the Shikra MDSS display subsystem on the Qualcomm Shikra CQM EVK board
and add the DLC0697 MIPI DSI display panel node. Pin pm4125_l5 to 1.232V with
regulator-allow-set-load for DSI PHY PLL stability.

> diff --git a/arch/arm64/boot/dts/qcom/shikra-cqm-evk.dts b/arch/arm64/boot/dts/qcom/shikra-cqm-evk.dts
> index 6ad90df3b4156..c426691644573 100644
> --- a/arch/arm64/boot/dts/qcom/shikra-cqm-evk.dts
> +++ b/arch/arm64/boot/dts/qcom/shikra-cqm-evk.dts
[ ... ]
> @@ -23,6 +23,86 @@ aliases {
>  	chosen {
>  		stdout-path = "serial0:115200n8";
>  	};
[ ... ]
> +	vreg_wled: regulator-wled {
> +		compatible = "regulator-fixed";
> +		regulator-name = "vreg_wled";
> +		gpio = <&tlmm 91 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +	};
> +};
[ ... ]
> +	panel@0 {
> +		compatible = "dlc,dlc0697", "ilitek,ili7807s";
> +		reg = <0>;
> +
> +		reset-gpios = <&tlmm 3 GPIO_ACTIVE_LOW>;
> +
> +		vddi-supply = <&pm4125_l15>;
> +		avdd-supply = <&vreg_disp_p>;
> +		avee-supply = <&vreg_disp_n>;
> +		wled-supply = <&vreg_wled>;

[Severity: High]
Will the display backlight remain unpowered here?

Looking at the driver for this panel in
drivers/gpu/drm/panel/panel-ilitek-ili7807s.c:ili7807s_supplies:

static const struct regulator_bulk_data ili7807s_supplies[] = {
	{ .supply = "vddi" },
	{ .supply = "avdd" },
	{ .supply = "avee" },
};

The driver only requests the vddi, avdd, and avee supplies during device
initialization. It does not parse or request the wled-supply assigned to it.

Because vreg_wled is not configured as regulator-always-on and no active
driver requests it, the regulator framework will never drive GPIO 91 high to
enable the WLED power supply.

While the driver registers a DCS backlight that sends MIPI DCS commands to set
brightness, the actual backlight LED circuitry requires power from vreg_wled.

Without the driver enabling this regulator, will the display backlight
remain unpowered on boot?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260930-shikra-dt-changes-v5-0-8eaf658a0e38@oss.qualcomm.com?part=3