Re: [PATCH net 1/2] net: pse-pd: si3474: keep detection enabled on the other PIs

[Kory Maincent <kory.maincent@bootlin.com>]

On 10/19/26 18:24, Piotr Kubik wrote:
> DETECT_CLASS_ENABLE holds the detection and classification bits of
> all four channels of a quad. si3474_pi_enable() wrote the register
> with the bits of its own PI only, so it cleared them for the other PI
> of the quad. In AUTO mode that PI keeps its admin state and a PD that
> already has power keeps it, but the port runs no new detection: a PD
> plugged in later, or one waiting for detection when the other PI is
> enabled, gets no power.
> 
> Read the register and set the PI bits, as the PORT_MODE update above
> already does.
> 
> Discovered by an AI code review agent. Confirmed on an SDG-9000 board
> (MediaTek MT7988A, two Si3474 in AUTO pin mode) with Linux 6.18:
> with both PIs of one quad disabled, enabling PI A and then PI B left
> DETECT_CLASS_ENABLE with the bits of PI B only, and a PD on PI A never
> got power. No kernel change was needed to reproduce it.
> 
> Tested on the same board with the same sequence in both orders:
> DETECT_CLASS_ENABLE keeps the bits of both PIs, and the PD gets power.
> No kernel selftest covers PSE hardware.

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

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