Re: [PATCH net-next v12 2/4] net: pse-pd: add Realtek PSE MCU core

On Sun,  9 Aug 2026 11:22:48 +0000
Jonas Jelonek <[email protected]> wrote:

> A range of managed Realtek-based PoE switches use a small microcontroller
> on the PCB to front the actual PSE silicon. The host CPU talks to that
> MCU over I2C/SMBus or UART using a fixed 12-byte request/response
> protocol with a trailing checksum; the PSE chips are managed by the MCU
> and are not accessed directly. Two generations of the protocol exist -
> both Realtek's - diverging in opcode numbering and a few response
> layouts; the driver handles this with a per-dialect opcode table and
> parser hooks for the responses that differ, selected by the compatible.
> The specific PSE chip behind the MCU is detected at runtime and only
> influences per-chip constants (power scaling and the per-port cap).
> 
> This core module implements the protocol, message framing, the dialect
> machinery and the pse_controller_ops glue, and exports a registration
> helper for transport modules. The I2C and UART transports that drive it
> follow in the next patches; the core (PSE_REALTEK_MCU) is selected
> automatically by those transports and is not user-selectable on its own.
> 
> The realtek-pse-mcu-* files and PSE_REALTEK_MCU* symbols match the
> realtek,pse-mcu-* compatibles (see the binding for the naming rationale).
> The two protocol generations - gen1 on older Broadcom-PSE boards, gen2 on
> Realtek's own PSE silicon - are both Realtek's, handled by the same shared
> core, each selecting its dialect via the compatible.
> 
> Power budgeting is left to the MCU firmware; the driver advertises
> PSE_BUDGET_EVAL_STRAT_DYNAMIC accordingly.

Reviewed-by: Kory Maincent <[email protected]>

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