From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64D06C2D0E4 for ; Fri, 27 Nov 2020 09:17:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11E0021D7F for ; Fri, 27 Nov 2020 09:17:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727750AbgK0JQ5 (ORCPT ); Fri, 27 Nov 2020 04:16:57 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:51681 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725875AbgK0JQ5 (ORCPT ); Fri, 27 Nov 2020 04:16:57 -0500 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4Cj8C92TpMz1qtdL; Fri, 27 Nov 2020 10:16:52 +0100 (CET) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 4Cj8C84Tq9z1sy8T; Fri, 27 Nov 2020 10:16:52 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id Hlz0i54BBvVV; Fri, 27 Nov 2020 10:16:50 +0100 (CET) X-Auth-Info: dpfPVe1hPmNWlW+Q/vLI2GSLKIjsjgRdBsMJ0e9s11A= Received: from jawa (89-64-5-98.dynamic.chello.pl [89.64.5.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Fri, 27 Nov 2020 10:16:50 +0100 (CET) Date: Fri, 27 Nov 2020 10:16:15 +0100 From: Lukasz Majewski To: Andrew Lunn Cc: Vladimir Oltean , Fugang Duan , "David S . Miller" , Jakub Kicinski , netdev@vger.kernel.org, Fabio Estevam , Vivien Didelot , NXP Linux Team , Florian Fainelli , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Peng Fan , stefan.agner@toradex.com, krzk@kernel.org, Shawn Guo Subject: Re: [RFC 0/4] net: l2switch: Provide support for L2 switch on i.MX28 SoC Message-ID: <20201127101615.7349b35f@jawa> In-Reply-To: <20201127005502.GQ2075216@lunn.ch> References: <20201125232459.378-1-lukma@denx.de> <20201126123027.ocsykutucnhpmqbt@skbuf> <20201127003549.3753d64a@jawa> <20201127005502.GQ2075216@lunn.ch> Organization: denx.de X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; boundary="Sig_/BICa7OL/1Ul3q5t3kEEq_yA"; protocol="application/pgp-signature" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --Sig_/BICa7OL/1Ul3q5t3kEEq_yA Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Hi Andrew, > > (A side question - DSA uses switchdev, so when one shall use > > switchdev standalone?) =20 >=20 > DSA gives you a framework for an Ethernet switch connected to a host > via Ethernet for the data plane. Generally, that Ethernet link to the > switch is a MAC to MAC connection. It can be PHY to PHY. But those are > just details. The important thing is you use an Ethernet driver on the > host. >=20 > If you look at pure switchdev devices, they generally DMA frames > directly into the switch. There is either one DMA queue per switch > port, or there is a way to multiplex frames over one DMA queue, > generally by additional fields in the buffer descriptor. >=20 > For this device, at the moment, it is hard to say which is the best > fit. A lot will depend on how the FEC driver works, if you can reuse > it, while still having the degree of control you need over the DMA > channel. If you can reuse the FEC driver, then a DSA driver might > work. If the coupling it too loose, and you have to take control of > the DMA, then a pure switchdev driver seems more appropriate. >=20 > Andrew >=20 Thanks for the detailed explanation. Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de --Sig_/BICa7OL/1Ul3q5t3kEEq_yA Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEgAyFJ+N6uu6+XupJAR8vZIA0zr0FAl/Aw98ACgkQAR8vZIA0 zr1EVAf+PndkSAVobok+I5hCS6pcZwgjc9jS944Kx4NLmKOd3Ckv/bebz9TUDuou P6veKuA53l3aUKaOjdCNntFPdVA1zntozoogSGA63O+LWjnxkqrkLqXUqzAjULmT Oo3QX7LctuMmrFPOWm7LVvETNx4BgSkuC8pBtjF1zUbp6H7O6uTFdhY7dBn1xmS6 onIfzHulhLPY6s+VDjIVvFJRtpNXfDBXBufcxDMTZ6sH/qs3CDk+9NWPb/f1FHRd P4+MSy7NV8FXFlZOqR2SeMPWzylGFVfJAiOcrl+3dl0/0IHP9gVkTOPt7bE3krda q7kXFFbpJRkLDPPwzF7AfBHvw2yxzw== =vIQY -----END PGP SIGNATURE----- --Sig_/BICa7OL/1Ul3q5t3kEEq_yA--