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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 24B0AC433B4 for ; Thu, 15 Apr 2021 21:03:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1E9560FDC for ; Thu, 15 Apr 2021 21:03:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235654AbhDOVD2 (ORCPT ); Thu, 15 Apr 2021 17:03:28 -0400 Received: from smtp-35.italiaonline.it ([213.209.10.35]:56210 "EHLO libero.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S235546AbhDOVDZ (ORCPT ); Thu, 15 Apr 2021 17:03:25 -0400 Received: from passgat-Modern-14-A10M.homenet.telecomitalia.it ([95.244.94.151]) by smtp-35.iol.local with ESMTPA id X98ZlquQZpK9wX98dlNmSe; Thu, 15 Apr 2021 23:03:00 +0200 x-libjamoibt: 1601 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=libero.it; s=s2021; t=1618520580; bh=Kvp5+D47MKZDrSKIysJWNf2xhpIp7NvSFWAyqEdkBPI=; h=From; b=zze3CLYsqtDa6dS/qz4LpoDb0dciwMJVlDch6uEkRu+nrJhbFD0SR9mBe8q96Yiiq wm6zq70f/qNHqbgfmQvQhUnB3ZoKCVTuk1o59GT+KgLEwIi3eDLg2U6pMMHgsBmigq ontLdY8kb9DrxZp/3CLcuuEOfcvje61/8HmGPjpARjSnklSVmz/Po6NOIcIvDGBRzY L8kSc15WJhPDNHtSZToLyYQEdpm+WeiFZW+V1FDZf6ZE9Bjv0wz9AaNaJ+7o8i9EqL PGBPDYYzadAkJNZUPqg/pqzm/A69yRDfmPYN2Wy8z4kZZmyNUE8W9HCSw5a78vUDCx 7MkqK9UutzANA== X-CNFS-Analysis: v=2.4 cv=A9ipg4aG c=1 sm=1 tr=0 ts=6078aa04 cx=a_exe a=ugxisoNCKEotYwafST++Mw==:117 a=ugxisoNCKEotYwafST++Mw==:17 a=RNOFN41U3FZ75c9ZyJUA:9 From: Dario Binacchi To: linux-kernel@vger.kernel.org Cc: Dario Binacchi , Dimitris Lampridis , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org Subject: [PATCH v3] serial: omap: fix rs485 half-duplex filtering Date: Thu, 15 Apr 2021 23:02:52 +0200 Message-Id: <20210415210252.25399-1-dariobin@libero.it> X-Mailer: git-send-email 2.17.1 X-CMAE-Envelope: MS4xfIrbi7z3i+m5hsETCrdGeYoVtrG3sy1gXbOe5zpMYGT5iv5aH0wegp3o6aw+84qjnLuxC+Unw33u58cYRlBHQwlWudzPWawaZpaBqSbSYI5efYBEQKD7 V1HhzB6Z3EPPZTqiA7U+DQp444/0yya1wXxfHZOfMAQDzP4MFFU4F+woNZrDVBNvQkC1vFdX0UBec1ViP6aZrHc2iRzdawWgs4BSHJmBm2fyk8oojf9qVFKg bcKZRWMnYA8eKBC2iPzS/HJYHJQUzFxgeYi4ySn8awSmmI+MFFayFfFo3u0ElERANuGsIwNzVkd7La4ERrWKpp7JR+2kkaP0WGjLLnnM03zJ58ZxSsx6GIiN gAquvgWxzW2yaTzkGoM9EzbxEA+ysThPqCv735n/V80xFTdHmcDOOdUsaOh8kl99IWd1ke9H Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Data received during half-duplex transmission must be filtered. If the target device responds quickly, emptying the FIFO at the end of the transmission can erase not only the echo characters but also part of the response message. By keeping the receive interrupt enabled even during transmission, it allows you to filter each echo character and only in a number equal to those transmitted. The issue was generated by a target device that started responding 240us later having received a request in communication at 115200bps. Sometimes, some messages received by the target were missing some of the first bytes. Fixes: 3a13884abea0 ("tty/serial: omap: empty the RX FIFO at the end of half-duplex TX") Signed-off-by: Dario Binacchi --- Changes in v3: - Add 'Fixes' tag Changes in v2: - Fix compiling error drivers/tty/serial/omap-serial.c | 39 ++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 15 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 76b94d0ff586..c0df22b7ea5e 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -159,6 +159,8 @@ struct uart_omap_port { u32 calc_latency; struct work_struct qos_work; bool is_suspending; + + atomic_t rs485_tx_filter_count; }; #define to_uart_omap_port(p) ((container_of((p), struct uart_omap_port, port))) @@ -328,19 +330,6 @@ static void serial_omap_stop_tx(struct uart_port *port) serial_out(up, UART_IER, up->ier); } - if ((port->rs485.flags & SER_RS485_ENABLED) && - !(port->rs485.flags & SER_RS485_RX_DURING_TX)) { - /* - * Empty the RX FIFO, we are not interested in anything - * received during the half-duplex transmission. - */ - serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_RCVR); - /* Re-enable RX interrupts */ - up->ier |= UART_IER_RLSI | UART_IER_RDI; - up->port.read_status_mask |= UART_LSR_DR; - serial_out(up, UART_IER, up->ier); - } - pm_runtime_mark_last_busy(up->dev); pm_runtime_put_autosuspend(up->dev); } @@ -366,6 +355,10 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr) serial_out(up, UART_TX, up->port.x_char); up->port.icount.tx++; up->port.x_char = 0; + if ((up->port.rs485.flags & SER_RS485_ENABLED) && + !(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) + atomic_inc(&up->rs485_tx_filter_count); + return; } if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) { @@ -377,6 +370,10 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr) serial_out(up, UART_TX, xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); up->port.icount.tx++; + if ((up->port.rs485.flags & SER_RS485_ENABLED) && + !(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) + atomic_inc(&up->rs485_tx_filter_count); + if (uart_circ_empty(xmit)) break; } while (--count > 0); @@ -420,7 +417,7 @@ static void serial_omap_start_tx(struct uart_port *port) if ((port->rs485.flags & SER_RS485_ENABLED) && !(port->rs485.flags & SER_RS485_RX_DURING_TX)) - serial_omap_stop_rx(port); + atomic_set(&up->rs485_tx_filter_count, 0); serial_omap_enable_ier_thri(up); pm_runtime_mark_last_busy(up->dev); @@ -491,8 +488,13 @@ static void serial_omap_rlsi(struct uart_omap_port *up, unsigned int lsr) * Read one data character out to avoid stalling the receiver according * to the table 23-246 of the omap4 TRM. */ - if (likely(lsr & UART_LSR_DR)) + if (likely(lsr & UART_LSR_DR)) { serial_in(up, UART_RX); + if ((up->port.rs485.flags & SER_RS485_ENABLED) && + !(up->port.rs485.flags & SER_RS485_RX_DURING_TX) && + atomic_read(&up->rs485_tx_filter_count)) + atomic_dec(&up->rs485_tx_filter_count); + } up->port.icount.rx++; flag = TTY_NORMAL; @@ -543,6 +545,13 @@ static void serial_omap_rdi(struct uart_omap_port *up, unsigned int lsr) return; ch = serial_in(up, UART_RX); + if ((up->port.rs485.flags & SER_RS485_ENABLED) && + !(up->port.rs485.flags & SER_RS485_RX_DURING_TX) && + atomic_read(&up->rs485_tx_filter_count)) { + atomic_dec(&up->rs485_tx_filter_count); + return; + } + flag = TTY_NORMAL; up->port.icount.rx++; -- 2.17.1