Re: [PATCH v1 2/2] arm64: dts: imx93-var-som-symphony: enable UART wakeup

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] arm64: dts: imx93: invalid and unused wakeup-source property on lpuart1
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commit 54c0e2db8b2c42ca5d07339b64a64c48881a16ab
Author: Stefano Radaelli <stefano.r@variscite.com>

arm64: dts: imx93-var-som-symphony: enable UART wakeup

This commit adds the wakeup-source property to the lpuart1 node in
imx93-var-som-symphony.dts to enable UART wakeup from system suspend.

> diff --git a/arch/arm64/boot/dts/freescale/imx93-var-som-symphony.dts b/arch/arm64/boot/dts/freescale/imx93-var-som-symphony.dts
> index 1f0954620195a..47203811abe99 100644
> --- a/arch/arm64/boot/dts/freescale/imx93-var-som-symphony.dts
> +++ b/arch/arm64/boot/dts/freescale/imx93-var-som-symphony.dts
> @@ -302,6 +302,7 @@ typec1_dr_sw: endpoint {
>  &lpuart1 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_uart1>;
> +	wakeup-source;

[Severity: Medium]
Is wakeup-source supported by the fsl-lpuart binding and driver here?

In arch/arm64/boot/dts/freescale/imx91_93_common.dtsi, lpuart1 uses the
compatible strings fsl,imx93-lpuart, fsl,imx8ulp-lpuart, and
fsl,imx7ulp-lpuart, which bind against
Documentation/devicetree/bindings/serial/fsl-lpuart.yaml. That schema
only references serial.yaml and rs485.yaml and specifies:

    unevaluatedProperties: false

Neither fsl-lpuart.yaml, serial.yaml, nor rs485.yaml defines
wakeup-source, so adding it to &lpuart1 causes a dtbs_check validation
failure.

In addition, neither lpuart_probe() in drivers/tty/serial/fsl_lpuart.c
nor serial_core_add_one_port() in drivers/tty/serial/serial_core.c parses
wakeup-source from the UART DT node. Instead, serial_core_add_one_port()
unconditionally marks the tty device wakeup-capable (leaving wakeup
disabled until enabled via sysfs), and lpuart_uport_is_active() checks
that tty device:

drivers/tty/serial/serial_core.c:serial_core_add_one_port() {
    ...
	if (!IS_ERR(tty_dev)) {
		device_set_wakeup_capable(tty_dev, 1);
	}
    ...
}

drivers/tty/serial/fsl_lpuart.c:lpuart_uport_is_active() {
    ...
		may_wake = tty_dev && device_may_wakeup(tty_dev);
    ...
}

Does this property actually have any effect without corresponding binding
and driver support?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1793645417.git.stefano.r@variscite.com?part=2