From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (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 ECBA8F9D9; Sat, 28 Mar 2026 22:10:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774735849; cv=none; b=Og6J/YW3oFWHPJUh/uaPD5Rt9cLJYPEcdoGu6i1NbEZXv2qi661xbJTiD63BRTixuauFtkNiN29M70xocCsW7eu1d6gus/phqy9Jl17HZIi78fXmly/xsJqkUeiilWntKM2XDeEzEnUAXaBoP3FKUpWJGa+zaTh3EuwJd/eGwXc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774735849; c=relaxed/simple; bh=iCTYI9LuFiPlopteCbwNN76nGCEOa5sLbzNABrenOxY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=i3FP+0DqgdAP6ra6SU1ZCQzp8FtTbhreSxSVnaa1NZdoBQOxQqIbYtogJgPqNZodmyZy3jaa9Ut0EUQ73SOfVpUwTNhhKK6fJ20iA4I43npx1OtQALeZHkhcMzZFTCHMAnjvsiV/v++JrhRnm//9yVzeVhIaT6tRYnVi0enjwOI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=D3vOlMJb; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="D3vOlMJb" 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=7+xh8xiXpqUgP1uEid640mnPB3EZMrtDdY9UTyqroGY=; b=D3vOlMJbnGqpNn4an25eNAtvWF B/slxqKYvhomBdo2gVhmpHGgi033xLSPycU9KEUBETVlus4PgJjvQIndxde2vpJSeCh3tACG895ZT hOAa3BjIr5AvWbsludiQKoX9ZjVQQNXJuVbuuuHn8uBeoMAJFytAWPWnRIMQ2kaE4+8FbWHdFWM3a lEue1zaaTEC2eZlG0cX6+WA7pf3KoljFZ8Pj1rAbaJe1ceST1P+0wYPKLzXg1Jbgn3nk2+N3n9xpJ uipDFsqQruLuzfE7V0aavXx/QYZXH34SMoLzJ5vprREypuQQFGJcCzHEzsEg1iJcoP1vR1JpZIdlM iAFx6BWA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:42570) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1w6brc-000000007VZ-2kTK; Sat, 28 Mar 2026 22:10:40 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1w6bra-0000000012B-36Yt; Sat, 28 Mar 2026 22:10:38 +0000 Date: Sat, 28 Mar 2026 22:10:38 +0000 From: "Russell King (Oracle)" To: Jan Hoffmann Cc: Jakub Kicinski , Andrew Lunn , Heiner Kallweit , "David S. Miller" , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] net: sfp: add quirk for ZOERAX SFP-2.5G-T Message-ID: References: <20260325164034.1542787-1-jan@3e8.eu> <20260327205020.1c020731@kernel.org> <58089a15-61e4-4899-b74f-2f5a495a206c@3e8.eu> 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: <58089a15-61e4-4899-b74f-2f5a495a206c@3e8.eu> Sender: Russell King (Oracle) On Sat, Mar 28, 2026 at 09:02:34PM +0100, Jan Hoffmann wrote: > On 2026-03-28 at 04:50, Jakub Kicinski wrote: > > On Wed, 25 Mar 2026 17:35:58 +0100 Jan Hoffmann wrote: > > > This is a 2.5G copper module which appears to be based on a Motorcomm > > > YT8821 PHY. There doesn't seem to be a usable way to to access the PHY > > > (I2C address 0x56 provides only read-only C22 access, and Rollball is > > > also not working). > > > > > > The module does not report the correct extended compliance code for > > > 2.5GBase-T, and instead claims to support SONET OC-48 and Fibre Channel: > > > > > > Identifier : 0x03 (SFP) > > > Extended identifier : 0x04 (GBIC/SFP defined by 2-wire interface ID) > > > Connector : 0x07 (LC) > > > Transceiver codes : 0x00 0x01 0x00 0x00 0x40 0x40 0x04 0x00 0x00 > > > Transceiver type : FC: Multimode, 50um (M5) > > > Encoding : 0x05 (SONET Scrambled) > > > BR Nominal : 2500MBd > > > > > > Despite this, the kernel still sets 2500Base-X as interface mode based > > > on the (incorrect) nominal signaling rate. > > > > > > However, it is also necessary to disable auto-negotiation for the module > > > to actually work. Thus, create a SFP quirk to do this. > > > > > > Signed-off-by: Jan Hoffmann > > > --- > > > Note: I'm not quite sure "sfp_quirk_disable_autoneg" is enough here, or > > > if it would be appropriate to use the full "sfp_quirk_oem_2_5g" quirk > > > due to the not really correct compliance code / nominal signaling rate. > > > > I'm no SFP expert but just going by the naming I strongly suspect that > > the module is the same hardware as "SFP-2.5G-T" from "FS", so keeping > > quirks consistent makes sense? > Based on commit e27aca3760c0 ("net: sfp: enhance quirk for Fibrestore 2.5G > copper SFP module"), the FS module uses an RTL8221B PHY, so it is different > hardware. And it also supports the Rollball protocol for PHY access, unlike > this Zoerax module. > > From the existing quirks, the only valid alternative I see for the Zoerax > module would be "sfp_quirk_oem_2_5g" (which also sets the additional bits > for 2500Base-T link mode and explicitly enables 2500Base-X interface mode). > But as that is not strictly necessary for making this particular module > work, I am unsure if using this quirk would be appropriate. See commit 50e96acbe11667b6fe9d99e1348c6c224b2f11dd which added this function. This was for an OEM SFP-2.5G-T where the PHY was similarly inaccessible, can only run at 2500base-X without inband and offers 2500Base-T connectivity. This is basically the same as your Zoerax module. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!