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 235F21F7586; Wed, 27 Aug 2025 08:45:37 +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=1756284339; cv=none; b=gpe4jKgPCjF6tkBrBNQA3UmYWyZIX2nJAZEv5REi09+bq3dQl+SpeQL/C3mWNHLi+8bbwjxqqFnDgqoJ+j0tyYivQ4NMY3ylnUpcGRpaR5OQ2FCjOWUYh3SN5vy5pp+dKXgTHFTsuVtk+8Rn14Rp0bYOmPnIYlOLgStNK+0xh9o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756284339; c=relaxed/simple; bh=qL+aMfVB16VP6zKXPU4QdEutUKy6kqDQAzOZCBT3+SI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gaK5ETCLZy2chZcFsxNBsNvhupY9N0HIkND5l2jKSYC3in092aQLsc8hsrSYnJ5oWT6O9milXra9WukP4i0fmzXhynvHTop8wqm0kT71mzhaeFe7XDfZ1WHkATVxf/5ZUD93OES48r3ECZHTRhmntWgilIoCfk6SLW3DI6nyvUo= 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=Tg4hzYs8; 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="Tg4hzYs8" 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=5MnBsqYuGg+eyK4Yde3+M+2B8jdthYxqSMDrNff11io=; b=Tg4hzYs8Z0+zqY7R0XehbNF3gZ SwlF7pBNMDKfOn7FnPC79gPVHCu0phZpW/KOlnXHXU7r5bIZwOJ5rIhIkm4dT9G4sgYdTVzfCJNYY OTVP/l5PR4hQRVj4522hJI0TuKTGXYh1INGqWDffM3xc2zvVs7RmY5FQwWJG7E1Iw3drU70s4FzIy FymjBB+ICfrydSWGJT1MxRlClVTSGBkvpEEQRgOxCsTTo9mzuQy2tiYGQoqvR4uzG1tv5f8b3grSo GHNWe9vuz9u1XZHyKa8M4+VpqdD662XMVAsIY30tGH3zC87n9Je7/R6DnQefNCiWt9QQx8S3XZATj astELmpg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:53718) 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 1urBmd-000000000FJ-3Mub; Wed, 27 Aug 2025 09:45:31 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1urBmb-0000000023R-2GYL; Wed, 27 Aug 2025 09:45:29 +0100 Date: Wed, 27 Aug 2025 09:45:29 +0100 From: "Russell King (Oracle)" To: Alexander Wilhelm Cc: Vladimir Oltean , Andrew Lunn , Heiner Kallweit , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Aquantia PHY in OCSGMII mode? Message-ID: References: <20250804160037.bqfb2cmwfay42zka@skbuf> <20250804160234.dp3mgvtigo3txxvc@skbuf> <20250805102056.qg3rbgr7gxjsl3jd@skbuf> <20250806145856.kyxognjnm4fnh4m6@skbuf> 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: Sender: Russell King (Oracle) On Wed, Aug 27, 2025 at 10:32:27AM +0200, Alexander Wilhelm wrote: > Am Wed, Aug 27, 2025 at 09:08:24AM +0100 schrieb Russell King (Oracle): > > On Wed, Aug 27, 2025 at 07:57:28AM +0200, Alexander Wilhelm wrote: > > > Hi Vladimir, > > > > > > One of our hardware engineers has looked into the issue with the 100M link and > > > found the following: the Aquantia AQR115 always uses 2500BASE-X (GMII) on the > > > host side. For both 1G and 100M operation, it enables pause rate adaptation. > > > However, our MAC only applies rate adaptation for 1G links. For 100M, it uses a > > > 10x symbol replication instead. > > > > This sounds like a misunderstanding, specifically: > > > > "our MAC only applies rate adaptation for 1G links. For 100M, it uses > > 10x symbol replication instead." > > > > It is the PHY that does rate adaption, so the MAC doesn't need to > > support other speeds. Therefore, if the PHY is using a 2.5Gbps link > > to the MAC with rate adaption for 100M, then the MAC needs to operate > > at that 2.5Gbps speed. > > > > You don't program the MAC differently depending on the media side > > speed, unlike when rate adaption is not being used. > > You're right. The flow control with rate adaptation is controlled by PHY. The > MAC should remain on the 2.5Gbps speed. Therefore I wonder why it uses 10x > symbol repetition. As I say, someone is misunderstanding something. The PHY controls what happens at the different media speeds. I wonder whether the hardware engineer is thinking that the PHY is configured for SGMII mode at 100Mbps - whic his controlled by vendor 1 register 0x31b. If the 3 LSBs are 4, then it's using "OCSGMII" otherwise if 3, then it'll be as the hardware engineer states. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!