From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0FE612E8DF6; Tue, 14 Oct 2025 09:57:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760435834; cv=none; b=Rsb5tliP+cDt7DI8JghnuR8wpy0f2hFhbl7/FlzZfZfN0U805943f6E3EaV50p4q95ytsfMtyal4ARdF8UVd34L6eACABMe9add15tMdr5v61XVvCLqKrZ6RnHphlbThH9fJxh4sME/tOiO9JC2tsyuyBTW58WbIv/htd02hhmI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760435834; c=relaxed/simple; bh=PSxhzlfYJchGE7++P9YV8xhmL/vMOKoa8VkZCCAAhmY=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Ce9eYlGLnk+O+PL8ObcaSgkd5jU0FlhiBV/gv/qzc53wWLtKiVsAjHxzhkle1zQ3j0NZH1DREzCrHXq3InDccmBwR4a0lI1KgK4yETmMbHAmpCfvqpzop3pNebUeE/VyNpsma5r2/Fc1LmSKQdFEHKiPf5/srfAKhHxUmOUdprw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=UhMYHZK0; arc=none smtp.client-ip=185.246.84.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="UhMYHZK0" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 1894A1A1378; Tue, 14 Oct 2025 09:57:10 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id E2331606EC; Tue, 14 Oct 2025 09:57:09 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id AEE62102F2298; Tue, 14 Oct 2025 11:57:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1760435829; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=CCxEg1933Mu/rtrIAyhW9gFkerKbyouvT8otO1paF3E=; b=UhMYHZK045eQW4odGcFdLardF6thaeclqfI9pOGJE8Y+D2Akbs6PCOFPE67gGhvh614/8R BkdJ4fSMpc3Ow/qN2twzeylgemTd612xFDF3cBJf0vQsV7/kEJB0jIjvSkLJgj6+LZSl51 ijuI6GEmY1cVdvbkjPFXC1do095elko0YkmNR0XMKW6LwmBIonik8o0c8rZcMd5eusn+cW pi76Qekteo83yDsB1CbRR0mSrrWtZMcnT8aB6uLO6jigmgKXjH8/4jhq4lR6ts5qH+9TcW OWIcNAkWidxhUieVDOnpwTeMBuuD6my0FE3z6cOQnzci5QR15DZjAfz5FqO0Gg== Date: Tue, 14 Oct 2025 11:56:59 +0200 From: Kory Maincent To: Simon Horman Cc: Oleksij Rempel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Thomas Petazzoni , kernel@pengutronix.de, Dent Project , 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 Message-ID: <20251014115659.0e6fd10c@kmaincent-XPS-13-7390> In-Reply-To: References: <20251013-feature_pd692x0_reboot_keep_conf-v2-0-68ab082a93dd@bootlin.com> <20251013-feature_pd692x0_reboot_keep_conf-v2-3-68ab082a93dd@bootlin.com> Organization: bootlin X-Mailer: Claws Mail 4.2.0 (GTK 3.24.41; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 On Tue, 14 Oct 2025 09:58:56 +0100 Simon Horman wrote: > On Mon, Oct 13, 2025 at 04:05:33PM +0200, Kory Maincent wrote: > > From: Kory Maincent (Dent Project) > >=20 > > Detect when PSE hardware is already configured (user byte =3D=3D 42) and > > skip hardware initialization to prevent power interruption to connected > > devices during system reboots. > >=20 > > 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. > >=20 > > Signed-off-by: Kory Maincent =20 >=20 > Hi Kory, >=20 > Perhaps I'm over thinking things here. But I'm wondering > what provision there is for a situation whereby: >=20 > 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. >=20 > ... 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)conf= igure the controller at boot time. Regards, --=20 K=C3=B6ry Maincent, Bootlin Embedded Linux and kernel engineering https://bootlin.com