From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 735394C84A; Thu, 21 Sep 2023 18:11:24 +0000 (UTC) Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C09A572402; Thu, 21 Sep 2023 10:56:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=QISaqh9G4DzFpv5qasHYVcLuNJPZgvVZsAh/znxO66M=; b=VTNXQ5zmMk1xgow0SjFQvHt7VN 0OlTTyoPg7ZIpxBxeIU5typ9qHlfn0/xSso3I2iftYkpqJ634DTbhiaQtB5l3Wd87OYBZJNU2Bb6d eML8VrqhPP2DcRnLyCt8/fybhGJnmThXov9Re3ZPC+3fbPOkMd7IlkHUHiwD67n4Wd5Bgc6TD0sKM 0kAhDgWRq0aHFtC2k/M7p2kExzhACC/czUICFb7UJiHO+JpDzMVRg6nM/tqBqvNi2q0RTpXoNfn4n Hfy3Vn4bcwu0knjJwimf2lmh9X5OEEvxP2vZbojvJhogNjHL5KmgfH28RdQWEFu9Rhk/sdAtzXaRK Nl880l+g==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:54114) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1qjKMe-0004lU-0u; Thu, 21 Sep 2023 15:09:08 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1qjKMb-0003aw-Q8; Thu, 21 Sep 2023 15:09:05 +0100 Date: Thu, 21 Sep 2023 15:09:05 +0100 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Choong Yong Liang , Rajneesh Bhardwaj , David E Box , Hans de Goede , Mark Gross , Jose Abreu , Heiner Kallweit , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Marek =?iso-8859-1?Q?Beh=FAn?= , Jean Delvare , Guenter Roeck , Giuseppe Cavallaro , Alexandre Torgue , Jose Abreu , Maxime Coquelin , Richard Cochran , Philipp Zabel , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Wong Vee Khee , Jon Hunter , Jesse Brandeburg , Revanth Kumar Uppala , Shenwei Wang , Andrey Konovalov , Jochen Henneberg , David E Box , Andrew Halaney , Simon Horman , Bartosz Golaszewski , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, platform-driver-x86@vger.kernel.org, linux-hwmon@vger.kernel.org, bpf@vger.kernel.org, Voon Wei Feng , Tan Tee Min , Michael Sit Wei Hong , Lai Peter Jun Ann Subject: Re: [PATCH net-next v3 0/5] TSN auto negotiation between 1G and 2.5G Message-ID: References: <20230921121946.3025771-1-yong.liang.choong@linux.intel.com> <4caade36-d4be-4670-ac79-d9d00488293d@lunn.ch> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4caade36-d4be-4670-ac79-d9d00488293d@lunn.ch> Sender: Russell King (Oracle) X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_NONE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Thu, Sep 21, 2023 at 03:14:59PM +0200, Andrew Lunn wrote: > > Auto-negotiation between 10, 100, 1000Mbps will use > > in-band auto negotiation. Auto-negotiation between 10/100/1000Mbps and > > 2.5Gbps will work as the following proposed flow, the stmmac driver reads > > the PHY link status registers then identifies the negotiated speed. > > I don't think you replied to my comment. > > in-band is just an optimisation. It in theory allows you to avoid a > software path, the PHY driver talking to the MAC driver about the PHY > status. As an optimisation, it is optional. Linux has the software > path and the MAC driver you are using basically has it implemented. Sorry Andrew, I have to disagree. It isn't always optional - there are PHYs out there where they won't pass data until the in-band exchange has completed. If you try to operate out-of-band without the PHY being told that is the case, and program the MAC/PCS end not to respond to the in-band frames from the PHY, the PHY will report link up as normal (since it reports the media side), but no data will flow because the MAC facing side of the PHY hasn't completed. The only exception are PHYs that default to in-band but have an inband bypass mode also enabled to cover the case where the MAC/PCS doesn't respond to the inband messages. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!