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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 61F9FC433DF for ; Mon, 12 Oct 2020 15:58:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 221E22067C for ; Mon, 12 Oct 2020 15:58:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602518287; bh=LEwnypzSjtd++DNJpV6qTktXDbbYwzYkL50Dz6WMZuQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=fdhAizwpUA7vN26eZ9YlhoIj4oNY+kFNjWEtquY51ywDJg9wawjKakxtSKZXyEGcS qSZ+nHQcnEQ7G66MBmY5tbM/DjC3HB11lAqC2tf1XYqR12RRal3cSPny8zLTkOo9PG pDfYTxHKCUR0CK/dRLsZEIasaS9IaxTqYYp9fhQ4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730567AbgJLP6G (ORCPT ); Mon, 12 Oct 2020 11:58:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:53616 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726742AbgJLP6G (ORCPT ); Mon, 12 Oct 2020 11:58:06 -0400 Received: from kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com (unknown [163.114.132.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 660B52074A; Mon, 12 Oct 2020 15:58:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602518285; bh=LEwnypzSjtd++DNJpV6qTktXDbbYwzYkL50Dz6WMZuQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ypORsP7hseFygcpMSXloSyLUTY+6Zs3ggk+1uBiatnuOy0+sTaRiS7zw+TIly6Mb5 /IrkWHMPQvcw7vw6Tr0LUgZHUcjsjExU9lDCbr5fzKaPsIG7UlNZ1p8/dZ8efNbgnL zyNDI9LSupZftVGqTOlJeojLAKKy9jUiX0CAaweg= Date: Mon, 12 Oct 2020 08:58:03 -0700 From: Jakub Kicinski To: Danielle Ratson Cc: Ido Schimmel , "netdev@vger.kernel.org" , "davem@davemloft.net" , Jiri Pirko , "andrew@lunn.ch" , "f.fainelli@gmail.com" , "mkubecek@suse.cz" , mlxsw , Ido Schimmel , "johannes@sipsolutions.net" Subject: Re: [PATCH net-next 1/6] ethtool: Extend link modes settings uAPI with lanes Message-ID: <20201012085803.61e256e6@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: References: <20201010154119.3537085-1-idosch@idosch.org> <20201010154119.3537085-2-idosch@idosch.org> <20201011153759.1bcb6738@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 12 Oct 2020 15:33:45 +0000 Danielle Ratson wrote: > > What's the use for this in practical terms? Isn't the lane count basically > > implied by the module that gets plugged in? > > The use is to enable the user to decide how to achieve a certain speed. > For example, if he wants to get 100G and the port has 4 lanes, the > speed can be achieved it using both 2 lanes of 50G and 4 lanes of > 25G, as a port with 4 lanes width can work in 2 lanes mode with > double speed each. So, by specifying "lanes 2" he will achieve 100G > using 2 lanes of 50G. Can you give a concrete example of serdes capabilities of the port, what SFP gets plugged in and what configuration user wants to select?