From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20F72C433F5 for ; Tue, 5 Apr 2022 14:18:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379342AbiDEOPc (ORCPT ); Tue, 5 Apr 2022 10:15:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238449AbiDEJci (ORCPT ); Tue, 5 Apr 2022 05:32:38 -0400 Received: from ssl.serverraum.org (ssl.serverraum.org [176.9.125.105]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3207D6C; Tue, 5 Apr 2022 02:19:29 -0700 (PDT) Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id E1FF7221D4; Tue, 5 Apr 2022 11:19:27 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1649150368; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BOvj4u69nnl0MRspeEi8s3JMbY/tCVXYqntAM7FXoYM=; b=m3RUG0UMPDNFyI4gv+Ph23UcaiROlA2mhed7gN+Xme7uDlxgUwIZtiS2q3oJgilsF5toFx pHqXmbcoIlcQ6mNT9wgqyLFnA/NUyTxsASJRXOzUDrJgBRhSY3g6QlwFVEpdkUMvNFVx9p /nuXiThKwOhvWNzhZC9D6WKUNayp138= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 05 Apr 2022 11:19:27 +0200 From: Michael Walle To: Kurt Kanzenbach Cc: Andrew Lunn , richardcochran@gmail.com, davem@davemloft.net, grygorii.strashko@ti.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux@armlinux.org.uk, mlichvar@redhat.com, netdev@vger.kernel.org, qiangqing.zhang@nxp.com, vladimir.oltean@nxp.com Subject: Re: [PATCH RFC V1 net-next 3/4] net: Let the active time stamping layer be selectable. In-Reply-To: <877d83rjjc.fsf@kurt> References: <20220104014215.GA20062@hoboy.vegasvil.org> <20220404150508.3945833-1-michael@walle.cc> <877d83rjjc.fsf@kurt> User-Agent: Roundcube Webmail/1.4.13 Message-ID: X-Sender: michael@walle.cc Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). -michael