Re: [PATCH V2 RFC 2/2] ARM: dts: BCM5301X: change Luxul XWR-3150 CPU port from 5 do 8
From: Vladimir Oltean <olteanv@gmail.com>
Date: 2026-08-11 21:47:13
Also in:
linux-arm-kernel, linux-devicetree
On Tue, Aug 11, 2026 at 09:36:58PM +0200, Rafał Miłecki wrote:
From: Rafał Miłecki <rafal@milecki.pl> Northstar devices have 3 CPU ports (each connected to a different Ethernet interface). This design was meant for dual IMP setups when WAN traffic goes to port 5 and LAN traffic goes to port 8. For practical reasons we label only one of those ports as "cpu" (the rest remains disabled). It's because of Linux behaviour (and it's probably a bad thing since DT shouldn't "care" that that).
Did you see ds->ops->preferred_default_local_cpu_port()? You can define all CPU ports in the device tree as such, and let the driver select among them.
So far the choice of "cpu" port was based on how vendor decided to setup given device originally: which of three Ethernet interfaces got MAC assigned and which port was used by vendor original firmware. Most vendors decided to use CPU port 5 & relevant Ethernet interface. The problem is that only switch port 8 provides full functionality. Change the choice of "cpu" port to 8 and make the third Ethernet interface (connected to port 8) use MAC designed for the first Ethernet interface (connected to port 5). This makes Linux use switch in a feature full way. Signed-off-by: Rafał Miłecki <rafal@milecki.pl> --- This seems to be a slight abuse of DT. Instead of describing hardware we make it steer Linux into using a more appropriate switch port. This isn't strictly a setback on its own. It's a change from one choice to another. I'm not sure about that MAC however. We say that the third Ethernet interface should use MAC that was designed for the first one.
So the NVMEM is not provisioned for multiple MAC addresses for gmac0 and gmac2? Can they ever be used simultaneously? Even so, I'm not sure whether that would cause any problems (depending on whether the switch supports address learning on IMP ports, it might not). Do you have a specific concern?
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Is all of that acceptable? .../arm/boot/dts/broadcom/bcm47094-luxul-xwr-3150-v1.dts | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)diff --git a/arch/arm/boot/dts/broadcom/bcm47094-luxul-xwr-3150-v1.dts b/arch/arm/boot/dts/broadcom/bcm47094-luxul-xwr-3150-v1.dts index 8e487f60a2cc..7969f0f331b5 100644 --- a/arch/arm/boot/dts/broadcom/bcm47094-luxul-xwr-3150-v1.dts +++ b/arch/arm/boot/dts/broadcom/bcm47094-luxul-xwr-3150-v1.dts@@ -81,6 +81,11 @@ &gmac0 { nvmem-cell-names = "mac-address"; }; +&gmac2 { + nvmem-cells = <&et0macaddr 0>; + nvmem-cell-names = "mac-address"; +}; + &pcie_bridge0 { wifi@0,0 { compatible = "brcm,bcm4366-fmac", "brcm,bcm4329-fmac";@@ -136,7 +141,7 @@ port@4 { }; port@5 { - label = "cpu";
label = "cpu" doesn't really do anything and just confuses things. Labels are only defined for user ports. Please remove this property as a follow-up (or preparatory) change.
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+ status = "disabled"; }; port@7 {@@ -144,7 +149,7 @@ port@7 { }; port@8 { - status = "disabled"; + label = "cpu"; }; }; };-- 2.51.0