R: [PATCH 3/3] arm64: dts: marvell: Add Sophos XGS 107w NPU board

[Nicolò Giuliani - nicolo.giuliani6@studio.unibo.it]

Hi Andrew,

Thanks for the review.

> The reset line of the switch (CP GPIO2 pin 17) is deliberately not given
> to the mv88e6xxx driver as reset-gpios. The 88E6193X needs about two
> seconds after a reset before it can be used, much longer than the driver
> waits, so the probe would time out.
>
> The obvious question is, why is your 88E6193X special?

I don't think it is. I saw the probe time out when I started the kernel with kexec from the vendor Linux, so nothing had reset the switch before the driver did. When the boot loader resets the switch first, which is how the board normally boots, probing with reset-gpios works on this board (Linux 6.18). I have not been able to test a driver-only reset yet, because the boot loader always resets the switch first, so I cannot say what made the difference. I have not checked whether an EEPROM is attached. v2 describes reset-gpios and drops the comment.

> +&cp0_i2c0 {
> [...]
> +     gpio@20 {
>
> Which port?

It is the LED expander of the eight RJ45 ports (two pins per port). Nothing uses it yet, so I dropped the node from v2. It can come back together with the LED nodes.

> +&cp0_i2c1 {
> +     /* SFP EEPROM (0x50/0x51) */
>
> The addresses are not that simple. When a copper module is inserted,
> other addresses are used. The SFP driver assumes it has access to all
> addresses on the bus.

Thanks, I had not considered copper modules. I removed the comment; the node now only enables the I2C bus of the SFP cage.

I will send v2 as a new thread after more feedback.

Thanks,
Nicolo Giuliani

________________________________________
Da: Andrew Lunn <andrew@xxxxxxx>
Inviato: domenica 20 settembre 2026 00:23
A: Nicolò Giuliani - nicolo.giuliani6@xxxxxxxxxxxxxxx
Cc: Rob Herring; Krzysztof Kozlowski; Conor Dooley; Gregory Clement; Sebastian Hesselbarth; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Oggetto: Re: [PATCH 3/3] arm64: dts: marvell: Add Sophos XGS 107w NPU board

> The reset line of the switch (CP GPIO2 pin 17) is deliberately not given
> to the mv88e6xxx driver as reset-gpios. The 88E6193X needs about two
> seconds after a reset before it can be used, much longer than the driver
> waits, so the probe would time out.

The obvious question is, why is your 88E6193X special?

I've seen issues when there is an EEPROM attached and it has a lot of
content to setup the switch. But that goes against using DSA, where
you want Linux to control the switch, not a fixed configuration.

> +&cp0_i2c0 {
> +     clock-frequency = <100000>;
> +     status = "okay";
> +
> +     /* Drives the port speed LEDs, which are not described yet */
> +     gpio@20 {

Which port?

> +&cp0_i2c1 {
> +     /* SFP EEPROM (0x50/0x51) */

The addresses are not that simple. When a copper module is inserted,
other addresses are used. The SFP driver assumes it has access to all
addresses on the bus.


  Andrew