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 4283A392C27 for ; Wed, 11 Mar 2026 14:26:19 +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=1773239180; cv=none; b=YOE7DgatI9Z2tybrLqO8PbHP3bUyRnACqmYaA2PMN04GCh0oQ3SSDW1pwN3yWYZwaCjbnFFTKwap1h3xM1A6L1JhHTwfARy5IXFO30CbfgWJlpP72JXlHpN7d99sZHnDlTHpyK/7k7NqSuksMb9GC5ny4iwBa0S1GYbgQyMeX8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773239180; c=relaxed/simple; bh=4ceUNuXX6pWUvU8VvO1XDBzl8/ZMKu+p+vbNJlMs9wY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A9ceReDOkl9582jutfOC8+H0Ok0t6JVji08tMwIIdHYjV/fpG4iscqO7hAhq+CrBmbNCZnZ/sOYxo72QgIZQyDHlW6dONDsBA7Wru6tn6iQSsU6Pyimc416nwzXaijs+7Qc4fGAc/fvtNCtuE8EVCVWr7OZT1FYMfZsa1qkdLmQ= 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=If8uo/u9; 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="If8uo/u9" 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=11YlZnsUQzWnNst822K7eoXd8kxt6rzmcbVMr2uy4Lc=; b=If8uo/u9Auvd7+rrMk9k7Qek3q 9ptxQOfM2dhiWqWfXsvF2GLny+7Mk7grOH4y9ADF5f5FwbPfXKkGgDowPgIa+YrfIx4paWTrrl4aI SZfUKZyrgXsNTeXFOK/cNEgyQ3f6PPIpdbs7CtieOOP/pahOrhhhe0yH4SCnqUJIn2YlsJCN9BOve r8E8ORDNAP5nAL03BRQcoluFBZNb9+xDeCl5OfYx8DZfGRzeaz0dNSd6gcsaDQ1//HvoJfnQ4iend o4ZyPsgVU2kTROZJi/h0QsjoKI2XwcvUlHj920lvnhuMafoEKCz6iIscxM4nEf64+nvKA1E8O/0ik wg9rGovA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44788) 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 1w0KVp-000000006Tx-2h7t; Wed, 11 Mar 2026 14:26:13 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1w0KVn-000000006Iv-3UY6; Wed, 11 Mar 2026 14:26:11 +0000 Date: Wed, 11 Mar 2026 14:26:11 +0000 From: "Russell King (Oracle)" To: Geert Uytterhoeven Cc: andrew@lunn.ch, conor@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, netdev@vger.kernel.org, pabeni@redhat.com Subject: Re: [PATCH net-next] net: phy: vitesse: add inband caps and configuration Message-ID: References: <20260311140135.937544-1-geert+renesas@glider.be> 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: <20260311140135.937544-1-geert+renesas@glider.be> Sender: Russell King (Oracle) On Wed, Mar 11, 2026 at 03:01:35PM +0100, Geert Uytterhoeven wrote: > Hi Russell, > > On Wed, 11 Mar 2026 at 01:07, Russell King wrote: > > Add support for VSC8662 reporting its inband capabilities, and also > > hook to configure the PHY's inband mode. > > > > This fixes a regression in the macb driver caused by commit > > 1338cfef1ff1 ("net: macb: fix SGMII with inband aneg disabled") > > Fixes: 1338cfef1ff1b958 ("net: macb: fix SGMII with inband aneg disabled") > > > Reported-by: Conor Dooley > > Link: https://lore.kernel.org/r/20260304-nebulizer-rounding-40fbc81a2ba1@spud > > s/Link/Closes/ I avoided it because any other PHY used with macb that is also connected via SGMII will run into this same issue. It just happens that adding this support fixes the above commit. Conversely, we have stmmac, which unconditionally enables SGMII inband at the MAC end no matter what phylink says to do, and should this PHY be used with this patch in a stmmac system, it will cause that to break, because we end up with either end misconfigured. Also, if this commit is applied without the macb change, you'll probably also find that macb breaks (please test that.) So, while this is a solution and a step forward, I'd rather not suggest that it is an official fix to the macb issue - it's merely filling in a missing piece of the jigsaw. Sadly, this is a fundamental issue with SGMII implementations today: whether SGMII inband is used/required is completely random both at the MAC/PCS end but also at the PHY end. If one ends up with a mismatch, then things stop working. As I say, the problem with fixing the PHY end of the link is that it could cause a different network driver to regress. So yes, this is a solution to the macb problem, but I regard it as high risk. That said, given the SGMII mess, there is no easy way forward. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!