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[73.241.114.122]) by smtp.gmail.com with ESMTPSA id l22sm12769150pjc.0.2019.12.26.17.52.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Dec 2019 17:52:34 -0800 (PST) Date: Thu, 26 Dec 2019 17:52:32 -0800 From: Richard Cochran To: Vladimir Oltean Cc: "Keller, Jacob E" , "davem@davemloft.net" , "jakub.kicinski@netronome.com" , "f.fainelli@gmail.com" , "vivien.didelot@gmail.com" , "andrew@lunn.ch" , "netdev@vger.kernel.org" Subject: Re: [PATCH net] net: dsa: sja1105: Fix double delivery of TX timestamps to socket error queue Message-ID: <20191227015232.GA6436@localhost> References: <20191216223344.2261-1-olteanv@gmail.com> <02874ECE860811409154E81DA85FBB58B26DEDC3@fmsmsx101.amr.corp.intel.com> <02874ECE860811409154E81DA85FBB58B26DF1C9@fmsmsx101.amr.corp.intel.com> <20191224190531.GA426@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Dec 26, 2019 at 08:24:19PM +0200, Vladimir Oltean wrote: > How will these drivers not transmit a second hw TX timestamp to the > stack, if they don't check whether TX timestamping is enabled for > their netdev? Ah, so they are checking SKBTX_HW_TSTAMP on the socket without checking for HWTSTAMP first? Yeah, that won't work with DSA time stamping. But who cares? Most of the real world doesn't have gigabit DSA switches in front of MACs that provide 10 gigabit links or higher. > Of course, at least that breakage is going to be much more binary and > obvious: PTP simply won't work at all for drivers stacked on top of > them until they are fixed. Right, you can fix individual MAC drivers to work with DSA, one by one. You are free to try to get the maintainers to ack your fixes. (But, here is a friendly hint: don't start out by declaring their drivers "broken"). > Does the TI PHYTER driver count? No. It really doesn't count. It won't work together with MAC time stamping, but this is a known limitation. That part is 100 mbit only, and there are very few implementations. Unfortunately the so_timestamping API did not foresee the possibility of simultaneous MAC and PHY time stamping. Too bad, that's life. I didn't invent the API, and I don't have to defend it, either. Thanks, Richard