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[73.241.114.122]) by smtp.gmail.com with ESMTPSA id j24sm9014488pff.71.2019.11.09.07.19.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 09 Nov 2019 07:19:45 -0800 (PST) Date: Sat, 9 Nov 2019 07:19:42 -0800 From: Richard Cochran To: Vladimir Oltean Cc: andrew@lunn.ch, f.fainelli@gmail.com, vivien.didelot@gmail.com, jakub.kicinski@netronome.com, davem@davemloft.net, netdev@vger.kernel.org Subject: Re: [PATCH net-next 0/3] Unlock new potential in SJA1105 with PTP system timestamping Message-ID: <20191109151942.GA1537@localhost> References: <20191109113224.6495-1-olteanv@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191109113224.6495-1-olteanv@gmail.com> 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 Sat, Nov 09, 2019 at 01:32:21PM +0200, Vladimir Oltean wrote: > The SJA1105 being an automotive switch means it is designed to live in a > set-and-forget environment, far from the configure-at-runtime nature of > Linux. Frequently resetting the switch to change its static config means > it loses track of its PTP time, which is not good. > > This patch series implements PTP system timestamping for this switch > (using the API introduced for SPI here: > https://www.mail-archive.com/netdev@vger.kernel.org/msg316725.html), > adding the following benefits to the driver: > - When under control of a user space PTP servo loop (ptp4l, phc2sys), > the loss of sync during a switch reset is much more manageable, and > the switch still remains in the s2 (locked servo) state. > - When synchronizing the switch using the software technique (based on > reading clock A and writing the value to clock B, as opposed to > relying on hardware timestamping), e.g. by using phc2sys, the sync > accuracy is vastly improved due to the fact that the actual switch PTP > time can now be more precisely correlated with something of better > precision (CLOCK_REALTIME). The issue is that SPI transfers are > inherently bad for measuring time with low jitter, but the newly > introduced API aims to alleviate that issue somewhat. > > This series is also a requirement for a future patch set that adds full > time-aware scheduling offload support for the switch. > > Vladimir Oltean (3): > net: dsa: sja1105: Implement the .gettimex64 system call for PTP > net: dsa: sja1105: Restore PTP time after switch reset > net: dsa: sja1105: Disallow management xmit during switch reset For the series: Acked-by: Richard Cochran