Re: [PATCH 4/4] arm64: dts: ti: k3-am62d2-evm: add out-band-wakeup property to m_can devices

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `out-band-wakeup` device tree property is added to `m_can` devices, but no C code in the kernel parses this property, making it completely inert. The commit message states this property is intended to allow the `out_band_wakeup` flag to be enabled during suspend. However, an exhaustive search of the kernel source confirms the string `"out-band-wakeup"` is not present in any C code, nor is it documented in the DT bindings. Neither the generic driver core nor the `m_can` driver reads this property or calls `device_set_out_band_wakeup()`. As a result, `dev->power.out_band_wakeup` will remain false, and the intended out-of-band wakeup functionality will not operate.
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--- Patch [4]: [PATCH 4/4] arm64: dts: ti: k3-am62d2-evm: add out-band-wakeup property to m_can devices ---
commit 7f02e9c8c4b2476d4793985a8f2b56891c451cf2
Author: Kendall Willis <[email protected]>

arm64: dts: ti: k3-am62d2-evm: add out-band-wakeup property to m_can devices

This commit adds the out-band-wakeup property to the mcu_mcan0 and mcu_mcan1
nodes in the k3-am62d2-evm device tree. It intends to enable the
out_band_wakeup flag during suspend for these devices.

> diff --git a/arch/arm64/boot/dts/ti/k3-am62d2-evm.dts b/arch/arm64/boot/dts/ti/k3-am62d2-evm.dts
> index f5ceb6a1b5deb..7f3c50a56ea87 100644
> --- a/arch/arm64/boot/dts/ti/k3-am62d2-evm.dts
> +++ b/arch/arm64/boot/dts/ti/k3-am62d2-evm.dts
> @@ -789,6 +789,7 @@ &c7x_0 {
>  };
>  
>  &mcu_mcan0 {
> +	out-band-wakeup;

[Severity: Medium]
Is the "out-band-wakeup" property actually parsed by the kernel?

Looking through the kernel source, there doesn't appear to be any C code
that parses the "out-band-wakeup" string, nor does it seem to be documented
in the DT bindings.

Neither the generic driver core nor the m_can driver appears to read this
property or call device_set_out_band_wakeup(), which would leave
dev->power.out_band_wakeup as false and prevent the intended out-of-band
wakeup functionality from operating.

Does this patch rely on another driver change that hasn't been merged yet?

>  	pinctrl-names = "default", "wakeup";
>  	pinctrl-0 = <&mcu_mcan0_tx_pins_default>, <&mcu_mcan0_rx_pins_default>;
>  	pinctrl-1 = <&mcu_mcan0_tx_pins_default>, <&mcu_mcan0_rx_pins_wakeup>;

[ ... ]

> @@ -800,6 +801,7 @@ &mcu_mcan0 {
>  };
>  
>  &mcu_mcan1 {
> +	out-band-wakeup;

[Severity: Medium]
Will this face the same issue where the property is ignored by the kernel?

>  	pinctrl-names = "default", "wakeup";
>  	pinctrl-0 = <&mcu_mcan1_tx_pins_default>, <&mcu_mcan1_rx_pins_default>;
>  	pinctrl-1 = <&mcu_mcan1_tx_pins_default>, <&mcu_mcan1_rx_pins_wakeup>;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=4