From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pidgin.makrotopia.org (pidgin.makrotopia.org [185.142.180.65]) (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 2533F2EC55C; Thu, 21 Aug 2025 18:37:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.142.180.65 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755801436; cv=none; b=Fgm4FVuzp3n1j4R+RBJP9JUXC3d5skCyXSF2r5rdk2+zvHQ7XAMrQnSv8C5oPFp4dSn4KJsuxOgAGAzXW5JMKfD+2+dOV1tbqu6N7gUzYOsR0FfZ8WUI/84DumAhPxf9FW+h6YYTWkV8BKp5usxUK5VfrXgCvb0EyUhSBC44PnY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755801436; c=relaxed/simple; bh=IBq99vyNZwAHZ/bm4xVJKwYr0fhcGKOPxJqxmkIyqT4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VUlxDSRsfwrQmp5EYPenkgDoadWAzIBx2SOW7RFPB9ZDOEZAsuF7bnuLcngoF2VAbj/DI7Y/qhi+ftjqU+SFRI7bJkUpBkD8VGf3aCpRXq73N/ioPqeFmN6tyE5nypFEO8QQ1nR0tjjIVR35rdXli5GjxI9rWJhuKHjZyWjLf/s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=makrotopia.org; spf=pass smtp.mailfrom=makrotopia.org; arc=none smtp.client-ip=185.142.180.65 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=makrotopia.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=makrotopia.org Received: from local by pidgin.makrotopia.org with esmtpsa (TLS1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.98.2) (envelope-from ) id 1upA9q-000000001Dn-14LS; Thu, 21 Aug 2025 18:37:06 +0000 Date: Thu, 21 Aug 2025 19:37:02 +0100 From: Daniel Golle To: "Sverdlin, Alexander" Cc: "hauke@hauke-m.de" , "olteanv@gmail.com" , "davem@davemloft.net" , "andrew@lunn.ch" , "linux@armlinux.org.uk" , "linux-kernel@vger.kernel.org" , "arkadis@mellanox.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "edumazet@google.com" , "f.fainelli@gmail.com" , "horms@kernel.org" , "netdev@vger.kernel.org" , "john@phrozen.org" , "Stockmann, Lukas" , "yweng@maxlinear.com" , "fchan@maxlinear.com" , "lxu@maxlinear.com" , "jpovazanec@maxlinear.com" , "Schirm, Andreas" , "Christen, Peter" , "ajayaraman@maxlinear.com" , "bxu@maxlinear.com" , "lrosu@maxlinear.com" Subject: Re: [PATCH RFC net-next 20/23] net: dsa: lantiq_gswip: add registers specific for MaxLinear GSW1xx Message-ID: References: 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: Hi Alenxander, thank you for the thorough review of the RFC series! On Thu, Aug 21, 2025 at 06:11:36PM +0000, Sverdlin, Alexander wrote: > On Sat, 2025-08-16 at 20:56 +0100, Daniel Golle wrote: > > [...] > > +#define GSW1XX_PORTS 6 > > a tricky questions for you ;-) > > There are scarce references to Port 6 across GSW145 datasheet, the 7th port. > One could also enable/disable it (bit P6) in GSWIP_CFG (0xF400). > > Yes, it's sold as 6-port switch, but the question is, shall the port 6 be > disabled to save power and avoid unnecessary EMI? I understood that port 6 can be used for packet injection or monitoring over the management interface (MDIO or SPI). For a moment I thought it'd be cool to implement a (very slow) Ethernet netdev allowing to use that feature in Linux -- but it would be very very slow and also useless on systems which anyway got either port 4 or 5 connected to the host as CPU port. I guess it is intended for basic managed switches which come with a simple microcontroller connected to the GSW1xx chip: ~1 MBit/s "Ethernet-over-MDIO" or (slightly faster due to duplex) "Ethernet-over-SPI" can be fast enough to serve a simple Web UI, Telnet, SSH, or respond to SNMP or LLDP, for example. I wonder if that port also supports the DSA special tag (insertion and egress)... Anyway, fantasies aside, at least for now it does make sense to disable it, though I wouldn't expect significant power saving or reduced EMI from that (but you never know...)