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Content-Language: en-US To: Kurt Kanzenbach , Michael Walle CC: Andrew Lunn , , , , , , , , , References: <20220104014215.GA20062@hoboy.vegasvil.org> <20220404150508.3945833-1-michael@walle.cc> <877d83rjjc.fsf@kurt> <87wng3pyjl.fsf@kurt> From: Grygorii Strashko In-Reply-To: <87wng3pyjl.fsf@kurt> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 05/04/2022 14:19, Kurt Kanzenbach wrote: > On Tue Apr 05 2022, Michael Walle wrote: >> Am 2022-04-05 11:01, schrieb Kurt Kanzenbach: >>> On Mon Apr 04 2022, Michael Walle wrote: >>>> That would make sense. I guess what bothers me with the current >>>> mechanism is that a feature addition to the PHY in the *future* (the >>>> timestamping support) might break a board - or at least changes the >>>> behavior by suddenly using PHY timestamping. >>> >>> Currently PHY timestamping is hidden behind a configuration option >>> (NETWORK_PHY_TIMESTAMPING). By disabling this option the default >>> behavior should stay at MAC timestamping even if additional features >>> are added on top of the PHY drivers at later stages. Or not? >> >> That is correct. But a Kconfig option has several drawbacks: >> (1) Doesn't work with boards where I might want PHY timestamping >> on *some* ports, thus I need to enable it and then stumple >> across the same problem. >> (2) Doesn't work with generic distro support, which is what is >> ARM pushing right now with their SystemReady stuff (among other >> things also for embeddem system). Despite that, I have two boards >> which are already ready for booting debian out of the box for >> example. While I might convince Debian to enable that option >> (as I see it, that option is there to disable the additional >> overhead) it certainly won't be on a per board basis. >> Actually for keeping the MAC timestamping as is, you'd need to >> convince a distribution to never enable the PHY timestamping >> kconfig option. >> >> So yes, I agree it will work when you have control over your >> kconfig options, after all (1) might be more academic. But I'm >> really concerned about (2). > > Yes, the limitations described above are exactly one of the reasons to > make the timestamping layer configurable at run time as done by these > patches. Seems like PHY TS support belongs to HW description category, so could it be device tree material, like generic property defining which layer should do timestamping? -- Best regards, Grygorii, Ukraine