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 6A18FEB64DC for ; Fri, 21 Jul 2023 10:06:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229847AbjGUKGH (ORCPT ); Fri, 21 Jul 2023 06:06:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231223AbjGUKGE (ORCPT ); Fri, 21 Jul 2023 06:06:04 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 149DAB7; Fri, 21 Jul 2023 03:06:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1689933963; x=1721469963; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=xwcGg3ySjrKkjK/u5gq0+w18B/u62vuaII+nleYZ4b0=; b=WdNWkxprAR9xjQof60ZCiP+YMEegrL7XQe8jmSLNvRgSitDO7a8N4wqC BLUngPJ4NOkPeaWc+uaIStX+wXoWR+qpgvDw3tcoSjdVF46jtPywlq6lI Ea9u5ERdj/ysjUk/aQwnWUm9n7wI+uUaGFS65DO+NwfeGJpWmCefQhJRN oBiXnxWkpFkXmvMMSRONSSMOeZnYlcyIr6n++4cAcbWHV8plgyFSoB5yH PqZ5upaw7gc5iLWQ+BiQjJ3usgMI9Im+ZNrwZW7TLZN/uLgMRTFxd+cvs W8VMPue5bk730uxlYOtdjm0F9Au0KEzTTZAaOvfaMl4uF61GYGZ1Dj0ni g==; X-IronPort-AV: E=McAfee;i="6600,9927,10777"; a="367025011" X-IronPort-AV: E=Sophos;i="6.01,220,1684825200"; d="scan'208";a="367025011" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2023 03:06:02 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10777"; a="718767951" X-IronPort-AV: E=Sophos;i="6.01,220,1684825200"; d="scan'208";a="718767951" Received: from smile.fi.intel.com ([10.237.72.54]) by orsmga007.jf.intel.com with ESMTP; 21 Jul 2023 03:05:55 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1qMn1B-00GqHL-1x; Fri, 21 Jul 2023 13:05:49 +0300 Date: Fri, 21 Jul 2023 13:05:49 +0300 From: Andy Shevchenko To: Tony Lindgren Cc: Greg Kroah-Hartman , Jiri Slaby , Dhruva Gole , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , John Ogness , Johan Hovold , Sebastian Andrzej Siewior , Vignesh Raghavendra , linux-omap@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: core: Add sysfs links for serial core port instances for ttys Message-ID: References: <20230719051613.46569-1-tony@atomide.com> <20230719054321.GJ5194@atomide.com> <20230720041319.GM5194@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230720041319.GM5194@atomide.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 20, 2023 at 07:13:19AM +0300, Tony Lindgren wrote: > * Andy Shevchenko [230719 13:59]: > > On Wed, Jul 19, 2023 at 08:43:21AM +0300, Tony Lindgren wrote: > > > * Andy Shevchenko [230719 05:34]: > > > > On Wed, Jul 19, 2023 at 08:16:11AM +0300, Tony Lindgren wrote: ... > > > > > And with this, we can add /dev/serial/by-id symlinks to the serial port > > > > > device instances so we can start using serial core port addressing in > > > > > addition to the legacy ttyS naming. > > > > > > > > > > The naming we can use is dev_name:0.0 where 0.0 are the serial core > > > > > controller id and port id, so for the ttyS0 example above the naming > > > > > would be 00:04.0:0.0. > > > > > > > > This is interesting idea. But any hint why it can be useful? > > > > > > If you have lots of serial ports and we are stuck with adding aliases > > > for the ports in the dts files where the ttyS naming and ordering does > > > not really help or may not necessarily make sense if the ports are on > > > different buses or domains. With CONFIG_SERIAL_8250_RUNTIME_UARTS=4, > > > the ttyS naming is only needed for the legacy ports really. > > > > I see. Does it fix the long standing issue with ttyS enumeration (on x86 > > at least) when depending on the presence of the legacy ports the HSUART > > (high speed) can preempt the legacy placeholders (ttyS0..ttyS3)? > > > > To me sounds like it may very well do fix it and I would be glad to see that > > in the commit message (as selling point) and in documentation. > > It won't affect how ttyS0..ttyS3 get assigned, but it helps finding your > HSUART instance with DEVNAME:0.0 style addressing. So you don't need to > care what ttyS number the port has. If you have such a test case maybe give > it a try. Exactly, the problem (currently) is, that depending on the BIOS settings the kernel can't use the same command line and this is quite a PITA for our customers! As far as we can specify hardware (path) to the console, it will be so cool and hopefully solves this very long standing issue. -- With Best Regards, Andy Shevchenko