From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753349AbbLCTpH (ORCPT ); Thu, 3 Dec 2015 14:45:07 -0500 Received: from mail-ig0-f177.google.com ([209.85.213.177]:37197 "EHLO mail-ig0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753022AbbLCTpE (ORCPT ); Thu, 3 Dec 2015 14:45:04 -0500 Subject: Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag for struct serial_rs485 To: "Matwey V. Kornilov" References: <1447338836-8785-1-git-send-email-matwey@sai.msu.ru> <1447338836-8785-3-git-send-email-matwey@sai.msu.ru> <20151112195707.5e9cb1d8@lxorguk.ukuu.org.uk> <5644F4F2.2080408@hurleysoftware.com> <20151114152536.693d964c@lxorguk.ukuu.org.uk> <564A2BF5.8030305@hurleysoftware.com> <564CC472.8010505@hurleysoftware.com> <565F7CA2.5030505@hurleysoftware.com> <56605491.1070206@hurleysoftware.com> Cc: One Thousand Gnomes , Greg KH , jslaby@suse.com, linux-kernel , linux-serial@vger.kernel.org From: Peter Hurley Message-ID: <56609BBC.8010806@hurleysoftware.com> Date: Thu, 3 Dec 2015 14:45:00 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/2015 12:29 PM, Matwey V. Kornilov wrote: > 2015-12-03 17:41 GMT+03:00 Peter Hurley : >> Hi Matwey, >> >> On 12/03/2015 12:50 AM, Matwey V. Kornilov wrote: >>> I am working on v4, where I completely redesigned implementation. And >>> now I think that it is considerably better than v3. >>> It looks like the following: >>> https://github.com/matwey/linux/commits/8520_rs485_v4 >>> But it is not ready yet, there is a bug somewhere. >>> >>> In the v4, each subdriver decides separately if it needs rs485 >>> emulation support. Then it enables it like the following: >>> https://github.com/matwey/linux/commit/4455e425fc045713fb921ccec695fe183f1558f0 >>> Before calling serial8250_rs485_emul_enabled, the driver enables >>> interrupt on empty shift register (they are always there for omap_). >> >> Looks good. >> >> Are you testing with CONFIG_SERIAL_8250_DMA=n first to simplify the >> debug effort? DMA adds a completely different tx path. > > Many thanks for the advice. I've just found that the bug is not in my code =) > Even with pure 4.3.0 I cannot open /dev/ttyS5 more than once. It just > hangs on open() and the process is in S+ state. Hmm, that's odd. So $ stty -a < /dev/ttyS5 hangs if something like below is running? $ cat > /dev/ttyS5 >> Also, before submission, please shorten the identifiers. And Greg hates >> functions returning bool so just expanded serial8250_rs485_emul_enabled() >> inline. > > Am I allowed to use `re' instead of rs485_emul in names? Long names and constructs tend to obscure the execution flow. Some of the names could be reduced where the meaning is obvious: serial8250_rts_on_send serial8250_rts_after_send serial8250_handle_start_timer serial8250_handle_stop_timer These two I would inline into their lone call site: serial8250_rs485_emul_startup() serial8250_rs485_emul_shutdown() serial8250_rs485_emul_start_tx => __start_tx_rs485 rs485_emul => sw485/em485/emul485/soft485 ? Or just rs485 (except for the field name and structs so as not to confuse it with the port->rs485) Just my 2ยข Regards, Peter Hurley