From: Kory Maincent <kory.maincent@bootlin.com>
To: Simon Horman <horms@kernel.org>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
kernel@pengutronix.de,
Dent Project <dentproject@linuxfoundation.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v2 3/3] net: pse-pd: pd692x0: Preserve PSE configuration across reboots
Date: Tue, 14 Oct 2025 11:56:59 +0200 [thread overview]
Message-ID: <20251014115659.0e6fd10c@kmaincent-XPS-13-7390> (raw)
In-Reply-To: <aO4Q0HIZ_72fwRI2@horms.kernel.org>
On Tue, 14 Oct 2025 09:58:56 +0100
Simon Horman <horms@kernel.org> wrote:
> On Mon, Oct 13, 2025 at 04:05:33PM +0200, Kory Maincent wrote:
> > From: Kory Maincent (Dent Project) <kory.maincent@bootlin.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@bootlin.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.
>
> ...
You have to find a way to turn off the power supply of the PSE controller.
As adding a devlink uAPI for this was not accepted, a hard reset for the
PSE controller is the only way to clean the user byte register and (re)configure
the controller at boot time.
Regards,
--
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2025-10-14 9:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-13 14:05 [PATCH net-next v2 0/3] Preserve PSE PD692x0 configuration across reboots Kory Maincent
2025-10-13 14:05 ` [PATCH net-next v2 1/3] net: pse-pd: pd692x0: Replace __free macro with explicit kfree calls Kory Maincent
2025-10-14 9:01 ` Simon Horman
2025-10-13 14:05 ` [PATCH net-next v2 2/3] net: pse-pd: pd692x0: Separate configuration parsing from hardware setup Kory Maincent
2025-10-14 9:02 ` Simon Horman
2025-10-13 14:05 ` [PATCH net-next v2 3/3] net: pse-pd: pd692x0: Preserve PSE configuration across reboots Kory Maincent
2025-10-14 8:58 ` Simon Horman
2025-10-14 9:56 ` Kory Maincent [this message]
2025-10-14 14:06 ` Simon Horman
2025-10-16 1:00 ` [PATCH net-next v2 0/3] Preserve PSE PD692x0 " patchwork-bot+netdevbpf
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