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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 152A5C433EF for ; Mon, 7 Mar 2022 09:49:54 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KBtwb4WmGz3bc1 for ; Mon, 7 Mar 2022 20:49:51 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=W28BMBpX; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=134.134.136.24; helo=mga09.intel.com; envelope-from=ilpo.jarvinen@linux.intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=W28BMBpX; dkim-atps=neutral Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KBtvr5bV2z30Ks for ; Mon, 7 Mar 2022 20:49:12 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1646646554; x=1678182554; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version:content-id; bh=zC3EygN9B67AQNPvzALqT8NwONoTEFy8bHC2L1G4njc=; b=W28BMBpXy598i6KxO4bY4gPGt9zVM5TTEksM0CK9+5j0ciB3OnZJve6t FMRaz+qPkhat8zNr6gakN/43e+5EOXlv25nbnIhzyIHdEL359ipJobi4K WqSqxNcdhtqVu2bi8meJgbr3kN8CDX9ctnuFpvIeOEdEQveWge1Co+DjB CgXKtWBuPaYckQi7PLEbRQ9jIGEMa9M0sIRzXccsckmJHKTqR+DOZJ+Wq aE0FPCmfK8p53EUfrLqjLzGt1BkEc1JAvc4jGghDAuyYhm7+nCQ2FWqps hVlLxCc++MXQo01+pupLlfUh99ByKQqvudFKTgpmmbRNAjVM9TurZizpo A==; X-IronPort-AV: E=McAfee;i="6200,9189,10278"; a="254080149" X-IronPort-AV: E=Sophos;i="5.90,161,1643702400"; d="scan'208";a="254080149" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2022 01:48:11 -0800 X-IronPort-AV: E=Sophos;i="5.90,161,1643702400"; d="scan'208";a="553088602" Received: from rabl-mobl2.ger.corp.intel.com ([10.252.54.114]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2022 01:48:03 -0800 Date: Mon, 7 Mar 2022 11:48:01 +0200 (EET) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Lukas Wunner Subject: Re: [RFC PATCH 6/7] serial: General support for multipoint addresses In-Reply-To: <20220306194001.GD19394@wunner.de> Message-ID: References: <20220302095606.14818-1-ilpo.jarvinen@linux.intel.com> <20220302095606.14818-7-ilpo.jarvinen@linux.intel.com> <20220306194001.GD19394@wunner.de> MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-971395012-1646646016=:1677" Content-ID: X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Heikki Krogerus , linux-sh@vger.kernel.org, LKML , "James E.J. Bottomley" , Max Filippov , Rich Felker , Paul Mackerras , sparclinux@vger.kernel.org, linux-api@vger.kernel.org, Jiri Slaby , linux-arch@vger.kernel.org, Yoshinori Sato , Helge Deller , linux-doc@vger.kernel.org, linux-serial , Matt Turner , linux-xtensa@linux-xtensa.org, Arnd Bergmann , Johan Hovold , Ivan Kokshaysky , Andy Shevchenko , Richard Henderson , Chris Zankel , Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Greg Kroah-Hartman , linux-mips@vger.kernel.org, linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-971395012-1646646016=:1677 Content-Type: text/plain; CHARSET=ISO-8859-15 Content-Transfer-Encoding: 8BIT Content-ID: <07d5f9f-7fe3-3c54-6566-1873a5191970@linux.intel.com> On Sun, 6 Mar 2022, Lukas Wunner wrote: > On Wed, Mar 02, 2022 at 11:56:05AM +0200, Ilpo Järvinen wrote: > > > This change is necessary for supporting devices with RS485 > > multipoint addressing [*]. > > If this is only used with RS485, why can't we just store the > addresses in struct serial_rs485 and use the existing TIOCSRS485 > and TIOCGRS485 ioctls? There's 20 bytes of padding left in > struct serial_rs485 which you could use. No need to add more > user-space ABI. It could if it is agreed that serial multipoint addressing is just a thing in RS-485 and nowhere else? In that case, there is no point in adding more generic support for it. > > [*] Technically, RS485 is just an electronic spec and does not > > itself specify the 9th bit addressing mode but 9th bit seems > > at least "semi-standard" way to do addressing with RS485. > > Is 9th bit addressing actually used by an Intel customer or was > it implemented just for feature completeness? I think this mode > isn't used often (I've never seen a use case myself), primarily > because it requires disabling parity. On what basis? ...The datasheet I'm looking at has a timing diagram with both D8 (9th bit) and parity so I think your information must be incorrect. I don't have direct contacts with customers but I'm told it's important for other org's customers. -- i. --8323329-971395012-1646646016=:1677--