Re: [PATCH v6 6/7] ARM: dts: microchip: sama5d27_wlsom1: read MAC address from QSPI SFDP

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Indefinite probe deferral for `macb0` network interface if the EUI-48 marker is unprogrammed or the nvmem layout driver is missing.
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--- Patch [6]: [PATCH v6 6/7] ARM: dts: microchip: sama5d27_wlsom1: read MAC address from QSPI SFDP ---
commit 8eba2f7e81780da2083cb3da12b2567024175fa6
Author: Manikandan Muralidharan <manikandan.m@microchip.com>

ARM: dts: microchip: sama5d27_wlsom1: read MAC address from QSPI SFDP

This commit exposes the factory-programmed EUI-48 as a mac-address cell
via the QSPI flash SFDP NVMEM provider. It points macb0 at this cell
to provide a stable MAC address on boards where U-Boot does not set one.

> diff --git a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts
> index 35a933eec5738..5e87bf04bc47c 100644
> --- a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts
> +++ b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts
[ ... ]
> @@ -97,6 +97,8 @@ uart6: serial@200 {
>  
>  &macb0 {
>  	status = "okay";
> +	nvmem-cells = <&mac_address_eui48>;
> +	nvmem-cell-names = "mac-address";

[Severity: High]
Will this cause an indefinite probe deferral for the macb0 interface if the
EUI-48 marker is unprogrammed or the nvmem layout driver is missing?

When the device tree statically links the macb0 interface to the
mac_address_eui48 nvmem cell, macb_probe() calls of_get_ethdev_address()
which internally calls of_nvmem_cell_get().

If the kernel is missing the microchip,sst26vf-sfdp-eui layout driver, the
nvmem core via nvmem_layout_module_get_optional() returns -EPROBE_DEFER
indefinitely.

Alternatively, if the layout driver is loaded but the board's flash chip
lacks an EUI-48, the layout driver gracefully returns 0 without adding the
cell. However, of_nvmem_cell_get() unconditionally returns -EPROBE_DEFER if
a cell is missing but an nvmem-layout node exists in the device tree:

ret = nvmem->layout ? -EPROBE_DEFER : -ENOENT;

In both scenarios, macb_probe() receives -EPROBE_DEFER and indefinitely
defers, breaking the intended fallback to a random MAC address and resulting
in a complete loss of network connectivity.

>  };

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260729043026.1811147-1-manikandan.m@microchip.com?part=6