From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (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 DCA7B1CD1E for ; Sat, 17 Feb 2024 06:47:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708152460; cv=none; b=DiVeFSFg69OZNljPemhseMn3BIWwDLUhqslMe+MsSmed281k6fDdakXcC5LcM/HsF8imabSfUgUH28HQGWlHO7KzlyM1txXzLXev3e51p4tIwnrG3YFAaM8qqWBROhKTJEbUDawfx7a4EQpqbyU/+pIKbwSHJ8S3tyLa4eQJWxk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708152460; c=relaxed/simple; bh=vct0oM2xD8QMdRPrjg/MRpA2z2oOXKzf3lvCs+WHSlo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hAw51f+g1U/C22Q+KL+aCgoiIQ3UhjXkASZi7Vf0uE7LEW+1IubzL1yIIdbozgR0Nc+UDwlz88TXg1VrGWKQ/SKURyntqVLMGJe65Y/sok01pJd8MyoXPAg1xESve426HM9Awlv1c1p9mljniuYLlk5Ot8InKV6jOr2NjK+eROI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1rbETO-0000dn-DO; Sat, 17 Feb 2024 07:46:54 +0100 Received: from [2a0a:edc0:2:b01:1d::c5] (helo=pty.whiteo.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rbETJ-001DUW-My; Sat, 17 Feb 2024 07:46:49 +0100 Received: from ore by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1rbETJ-00CtWH-1w; Sat, 17 Feb 2024 07:46:49 +0100 Date: Sat, 17 Feb 2024 07:46:49 +0100 From: Oleksij Rempel To: Andrew Lunn Cc: Rob Herring , Kory Maincent , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jonathan Corbet , Luis Chamberlain , Russ Weight , Greg Kroah-Hartman , "Rafael J. Wysocki" , Krzysztof Kozlowski , Conor Dooley , Mark Brown , Frank Rowand , Heiner Kallweit , Russell King , Thomas Petazzoni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, Dent Project Subject: Re: [PATCH net-next v3 14/17] dt-bindings: net: pse-pd: Add bindings for PD692x0 PSE controller Message-ID: References: <20240208-feature_poe-v3-0-531d2674469e@bootlin.com> <20240208-feature_poe-v3-14-531d2674469e@bootlin.com> <20240209145727.GA3702230-robh@kernel.org> <618be4b1-c52c-4b8f-8818-1e4150867cad@lunn.ch> <65099b67-b7dc-4d78-ba42-d550aae2c31e@lunn.ch> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-doc@vger.kernel.org Hi Kory, Can you please integrated this new insights to the PSE PI documentation. Instead of 1000BaseT only, please use 1000/2.5G/5G/10GBASE-T as documented in the spec. On Fri, Feb 16, 2024 at 08:47:14AM +0100, Oleksij Rempel wrote: > On Thu, Feb 15, 2024 at 06:51:55PM +0100, Andrew Lunn wrote: > > > Hm.. good question. I didn't found the answer in the spec. By combining all > > > puzzle parts I assume, different Alternative configurations are designed > > > to handle conflict between "PSE Physical Layer classification" and PHY > > > autoneg. > > > > > > Here is how multi-pulse Physical Layer classification is done: > > > https://img.electronicdesign.com/files/base/ebm/electronicdesign/image/2020/07/Figure_5.5f2094553a61c.png > > > > > > this is the source: > > > https://www.electronicdesign.com/technologies/power/whitepaper/21137799/silicon-labs-90-w-power-over-ethernet-explained > > > > > > To avoid classification conflict with autoneg. Assuming, PHY on PD side > > > will be not powered until classification is completed. The only source > > > of pulses is the PHY on PSE side (if it is not under control of software > > > on PSE side or Midspan PSE is used), so aneg pulses should be send on > > > negative PoE pair? This all is just speculation, I would need to ask > > > some expert or do testing. > > > > > > If this assumption is correct, PHY framework will need to know exact > > > layout of MDI-X setting and/or silent PHY until PSE classification is done. > > > > Ideally, we don't want to define a DT binding, and then find it is > > wrong for 1000BaseT and above and we need to change it. > > > > So, either somebody needs to understand 1000BaseT and can say the > > proposed binding works, or we explicitly document the binding is > > limited to 10BaseT and 100BaseT. > > I asked the internet and found the answer: Some PSE/PD implementations > are not compatible with 1000BaseT. > > See Figure 33–4—10BASE-T/100BASE-TX Endpoint PSE location overview. > Alternative B show a variant where power is injected directly to pairs > without using magnetics as it is done for Alternative A (phantom > delivery - over magnetics). > > I assume, the reasoning for this kind of design is simple - price. > Otherwise magnetics will have special requirements: > https://www.coilcraft.com/de-de/edu/series/magnetics-for-power-over-ethernet/ > > So, we have following variants of 2 pairs PoE: > +---------+---------------+-------------------+---------------------+--------------------+ > | Variant | Alternative | Polarity | Power Feeding Type | Compatibility with | > | | (a/b) | (Direct/Reverse) | (Direct/Phantom) | 1000BaseT | > +=========+===============+===================+=====================+====================+ > | 1 | a | Direct | Phantom | Yes | > +---------+---------------+-------------------+---------------------+--------------------+ > | 2 | a | Reverse | Phantom | Yes | > +---------+---------------+-------------------+---------------------+--------------------+ > | 3 | b | Direct | Phantom | Yes | > +---------+---------------+-------------------+---------------------+--------------------+ > | 4 | b | Reverse | Phantom | Yes | > +---------+---------------+-------------------+---------------------+--------------------+ > | 5 | b | Direct | Direct | No | > +---------+---------------+-------------------+---------------------+--------------------+ > | 6 | b | Reverse | Direct | No | > +---------+---------------+-------------------+---------------------+--------------------+ > > An advanced PSE may implement range of different variants direct in the PSE > controller or with additional ICs in the PSE PI. The same is about PD. > > Let's take as example PD-IM-7608M eval board: > https://www.microchip.com/en-us/development-tool/PD-IM-7608M > > According to the schematics: > https://ww1.microchip.com/downloads/en/DeviceDoc/PD-IM-7608M.zip > It supports only Variant 5 - Alternative B, with only one polarity, > and direct feeding without magnetics. > > The simple PD may support only one variant: > https://community.fs.com/article/troubleshooting-poe-errors.html > " the power modes of PSE and PD are other factors that may cause PoE > faults. There are three PoE modes: Alternative A, alternative B, and > 4-pair delivery. If a PD only supports PoE mode B power delivery, while > a PoE switch is based on Alternative A, as a result, the PD and PoE > switch can not work together." > > For this case, it will be good if systems knows supported modes, so user > can get this information directly. For example with ethtool > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |