linux-kernel - Re: [PATCH net-next v2 3/3] net: pse-pd: pd692x0: Preserve PSE configuration across reboots

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Message-ID: <aO4Q0HIZ_72fwRI2@horms.kernel.org>
Date: Tue, 14 Oct 2025 09:58:56 +0100
From: Simon Horman <horms@...nel.org>
To: Kory Maincent <kory.maincent@...tlin.com>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	kernel@...gutronix.de,
	Dent Project <dentproject@...uxfoundation.org>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 3/3] net: pse-pd: pd692x0: Preserve PSE
 configuration across reboots

On Mon, Oct 13, 2025 at 04:05:33PM +0200, Kory Maincent wrote:
> From: Kory Maincent (Dent Project) <kory.maincent@...tlin.com>
> 
> Detect when PSE hardware is already configured (user byte == 42) and
> skip hardware initialization to prevent power interruption to connected
> devices during system reboots.
> 
> Previously, the driver would always reconfigure the PSE hardware on
> probe, causing a port matrix reflash that resulted in temporary power
> loss to all connected devices. This change maintains power continuity
> by preserving existing configuration when the PSE has been previously
> initialized.
> 
> Signed-off-by: Kory Maincent <kory.maincent@...tlin.com>

Hi Kory,

Perhaps I'm over thinking things here. But I'm wondering
what provision there is for a situation whereby:

1. The driver configures the device
2. A reboot occurs
2. The (updated) driver wants to (re)configure the device
   with a different configuration, say because it turns
   out there was a bug in or enhancement to the procedure at 1.

...