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 X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D2B5C433E7 for ; Sat, 10 Oct 2020 22:55:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA59E2075E for ; Sat, 10 Oct 2020 22:55:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602370520; bh=c+6LMXEZzk1A7ncH7/sCGuE4n/FGZyKgDHsr3FeDQJM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=VDJ6eZr6qqAzPAmngQCWPvQH5WRoQJKpva1RDK7+ixG/JESPkxQKQRkj8ACSHxyxS aNDWtRne+4e2QP/66o8XDv1CSNr0vF7+rWQi+xT84x1Pk29zar9b8K60m46x7KfJX0 XI2In2ARDWCNh2DZSlLnZvi4dRqoF7a6DxA0Ttks= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389088AbgJJWzS (ORCPT ); Sat, 10 Oct 2020 18:55:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52032 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731435AbgJJTWZ (ORCPT ); Sat, 10 Oct 2020 15:22:25 -0400 Received: from kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com (unknown [163.114.132.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 99FC12237B; Sat, 10 Oct 2020 15:44:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602344662; bh=c+6LMXEZzk1A7ncH7/sCGuE4n/FGZyKgDHsr3FeDQJM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uE2WZWZ9o8F3vVGsdME6aFIsv4ylgXRKPxBisANoo3GaXljeSsDeWqMoPM1recgTu 7fhouVQI4iIYJvq0oBzjo7l6uK5rSqvNizYYUrTaclRlYjJFU9nsaFcWg94Ssu4iPs XYcbwa5PTVW4dBjRDu1EeKZQygJ3DwZbMeGuXKXQ= Date: Sat, 10 Oct 2020 08:44:21 -0700 From: Jakub Kicinski To: Oliver Hartkopp Cc: Marc Kleine-Budde , netdev@vger.kernel.org, davem@davemloft.net, linux-can@vger.kernel.org, kernel@pengutronix.de Subject: Re: [PATCH 08/17] can: add ISO 15765-2:2016 transport protocol Message-ID: <20201010084421.308645a2@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: References: <20201007213159.1959308-1-mkl@pengutronix.de> <20201007213159.1959308-9-mkl@pengutronix.de> <20201009175751.5c54097f@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, 10 Oct 2020 16:29:06 +0200 Oliver Hartkopp wrote: > >> diff --git a/net/can/Kconfig b/net/can/Kconfig > >> index 25436a715db3..021fe03a8ed6 100644 > >> --- a/net/can/Kconfig > >> +++ b/net/can/Kconfig > >> @@ -55,6 +55,19 @@ config CAN_GW > >> > >> source "net/can/j1939/Kconfig" > >> > >> +config CAN_ISOTP > >> + tristate "ISO 15765-2:2016 CAN transport protocol" > >> + default y > > > > default should not be y unless there is a very good reason. > > I don't see such reason here. This is new functionality, users > > can enable it if they need it. > > Yes. I agree. But there is a good reason for it. > The ISO 15765-2 protocol is used for vehicle diagnosis and is a *very* > common CAN bus use case. More common than j1939? (Google uses words like 'widely used' and 'common' :)) To give you some perspective we don't enable Ethernet vlan support by default, vlans are pretty common, too. > The config item only shows up when CONFIG_CAN is selected and then ISO > 15765-2 should be enabled too. I have implemented and maintained the > out-of-tree driver for ~12 years now and the people have real problems > using e.g. Ubuntu with signed kernel modules when they need this protocol. > > Therefore the option should default to 'y' to make sure the common > distros (that enable CONFIG_CAN) enable ISO-TP too. I understand the motivation, but Linus had pushed back on defaulting to 'y' many times over the years, please read this: https://lkml.org/lkml/2012/1/6/354 This really must not pop up on his screen as default 'y' when he does an oldconfig after pulling the networking tree..