Re: [PATCH net-next v8 1/4] dt-bindings: net: pse-pd: add bindings for Realtek PSE MCU

On Wed, 15 Jul 2026 07:55:25 +0000
Jonas Jelonek [off-list ref] wrote:

Add a binding for the microcontroller (MCU) that fronts the PSE silicon
on a range of managed Realtek-based switches. The host talks only to the
MCU, over I2C/SMBus or UART, using a fixed message-based protocol; the
PSE chips behind it never appear on the bus.

The device is the MCU together with its Realtek firmware: the firmware
and its host protocol are what the binding describes, not the
general-purpose microcontroller they run on. The PSE silicon behind the
MCU (Realtek or Broadcom) is reported by the MCU and detected at runtime,
so it is not described here - hence the 'realtek' vendor prefix.

Two protocol generations exist, both Realtek's, selected by the
compatible: gen1 on older boards (fronting Broadcom PSE silicon) and gen2,
the altered protocol used with Realtek's own PSE silicon. On an I2C
attachment the framing the MCU firmware expects is part of the compatible
as well - '-smbus' or raw '-i2c'; a UART attachment carries no framing
suffix, as the transport is given by the parent serial node.

Each board additionally carries a device-specific compatible that falls
back to one of the protocol compatibles above. Drivers bind on the
protocol compatible; the device-specific string identifies the board and
reserves a place for a future per-board quirk without having to retrofit
device trees already in the field.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>

Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>

Thank you!

-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com