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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 autolearn=ham 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 3BBBEC433DB for ; Mon, 15 Feb 2021 15:18:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D527464DA3 for ; Mon, 15 Feb 2021 15:18:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230207AbhBOPSW (ORCPT ); Mon, 15 Feb 2021 10:18:22 -0500 Received: from lists.nic.cz ([217.31.204.67]:57546 "EHLO mail.nic.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230359AbhBOPRL (ORCPT ); Mon, 15 Feb 2021 10:17:11 -0500 Received: from localhost (unknown [IPv6:2a0e:b107:ae1:0:3e97:eff:fe61:c680]) by mail.nic.cz (Postfix) with ESMTPSA id A7F5D140A60; Mon, 15 Feb 2021 16:16:28 +0100 (CET) Date: Mon, 15 Feb 2021 16:16:27 +0100 From: Marek Behun To: Russell King - ARM Linux admin Cc: Nathan Rossi , netdev@vger.kernel.org, Nathan Rossi , Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Jakub Kicinski Subject: Re: [PATCH] net: dsa: mv88e6xxx: prevent 2500BASEX mode override Message-ID: <20210215161627.63c3091c@nic.cz> In-Reply-To: <20210215145757.GX1463@shell.armlinux.org.uk> References: <20210215061559.1187396-1-nathan@nathanrossi.com> <20210215144756.76846c9b@nic.cz> <20210215145757.GX1463@shell.armlinux.org.uk> X-Mailer: Claws Mail 3.17.7 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Virus-Scanned: clamav-milter 0.102.2 at mail X-Virus-Status: Clean Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 15 Feb 2021 14:57:57 +0000 Russell King - ARM Linux admin wrote: > On Mon, Feb 15, 2021 at 02:47:56PM +0100, Marek Behun wrote: > > On Mon, 15 Feb 2021 06:15:59 +0000 > > Nathan Rossi wrote: > > > > > diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c > > > index 54aa942eed..5c52906b29 100644 > > > --- a/drivers/net/dsa/mv88e6xxx/chip.c > > > +++ b/drivers/net/dsa/mv88e6xxx/chip.c > > > @@ -650,6 +650,13 @@ static void mv88e6xxx_validate(struct dsa_switch *ds, int port, > > > if (chip->info->ops->phylink_validate) > > > chip->info->ops->phylink_validate(chip, port, mask, state); > > > > > > + /* Advertise 2500BASEX only if 1000BASEX is not configured, this > > > + * prevents phylink_helper_basex_speed from always overriding the > > > + * 1000BASEX mode since auto negotiation is always enabled. > > > + */ > > > + if (state->interface == PHY_INTERFACE_MODE_1000BASEX) > > > + phylink_clear(mask, 2500baseX_Full); > > > + > > > > I don't quite like this. This problem should be either solved in > > phylink_helper_basex_speed() or somewhere in the mv88e6xxx code, but near > > the call to phylink_helper_basex_speed(). > > > > Putting a solution to the behaviour of phylink_helper_basex_speed() it > > into the validate() method when phylink_helper_basex_speed() is called > > from a different place will complicate debugging in the future. If > > we start solving problems in this kind of way, the driver will become > > totally unreadable, IMO. > > If we can't switch between 1000base-X and 2500base-X, then we should > not be calling phylink_helper_basex_speed() - and only one of those > two capabilities should be set in the validation callback. I thought > there were DSA switches where we could program the CMODE to switch > between these two... There are. At least Peridot, Topaz and Amethyst support switching between these modes. But only on some ports. This problem happnes on Peridot X, I think. On Peridot X there are - port 0: RGMII - ports 9-10: capable of 1, 2.5 and 10G SerDes (10G via XAUI/RXAUI, so multiple lanes) - ports 1-8: with copper PHYs - some of these can instead be set to use the unused SerDes lanes of ports 9-10, but only in 1000base-x mode So the problem can happen if you set port 9 or 10 to only use one SerDes lane, and use the spare lanes for the 1G ports. On these ports 2500base-x is not supported, only 1000base-x (maybe sgmii, I don't remember) Marek