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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 20AF1C43381 for ; Sun, 31 Jan 2021 20:06:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFBA564DF5 for ; Sun, 31 Jan 2021 20:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231910AbhAaUGL convert rfc822-to-8bit (ORCPT ); Sun, 31 Jan 2021 15:06:11 -0500 Received: from unicorn.mansr.com ([81.2.72.234]:58566 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231519AbhAaTry (ORCPT ); Sun, 31 Jan 2021 14:47:54 -0500 X-Greylist: delayed 14344 seconds by postgrey-1.27 at vger.kernel.org; Sun, 31 Jan 2021 14:47:53 EST Received: from raven.mansr.com (raven.mansr.com [IPv6:2001:8b0:ca0d:8d8e::3]) by unicorn.mansr.com (Postfix) with ESMTPS id E5A2E15360; Sun, 31 Jan 2021 19:47:11 +0000 (GMT) Received: by raven.mansr.com (Postfix, from userid 51770) id DAD56219FCF; Sun, 31 Jan 2021 19:47:11 +0000 (GMT) From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Andy Shevchenko Cc: Greg Kroah-Hartman , Jiri Slaby , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] serial: 8250: add option to disable registration of legacy ISA ports References: <20210128172244.22859-1-mans@mansr.com> Date: Sun, 31 Jan 2021 19:47:11 +0000 In-Reply-To: (Andy Shevchenko's message of "Sun, 31 Jan 2021 21:25:33 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Shevchenko writes: > On Thursday, January 28, 2021, Mans Rullgard wrote: > >> On systems that do not have the traditional PC ISA serial ports, the >> 8250 driver still creates non-functional device nodes. This change >> makes only ports that actually exist (PCI, DT, ...) get device nodes. >> >> > > This is kinda ABI breakage. At least this will break x86 platforms with > HSUARTs (all modern ones) that are used in embedded systems. > > I think you would rather need an option to disable this and select it by > the platforms where it is known not to break anything. What exactly breaks? The new option is enabled by default, just like the one right beside it (SERIAL_8250_PNP), so nothing at all changes unless this is actively disabled. On a system that doesn't have those ports, any attempt to access the device nodes produces some kind of error. How is it breaking anything to not create device nodes for hardware that doesn't exist? -- Måns Rullgård