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=-18.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=ham 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 AD49BC433E9 for ; Mon, 28 Dec 2020 15:17:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B29222A84 for ; Mon, 28 Dec 2020 15:17:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731973AbgL1PRN (ORCPT ); Mon, 28 Dec 2020 10:17:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:59806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392557AbgL1PRK (ORCPT ); Mon, 28 Dec 2020 10:17:10 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 021CD223E8; Mon, 28 Dec 2020 15:16:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609168589; bh=RNBiK0q5L0B6y+ZBNc0VzEwVQ5u9W7D2nAPJra2HCzQ=; h=Subject:To:From:Date:From; b=OGRg0Pk0HCIKAbGnAKql+oi4YduxQ26IBUGp6r/oW9+39k007yG2a5p2s5No5dKgk W2j5hhxLD4pNT+XRzQBP0pImmPpJyV5uRtaOkXkcPuZFwIzz1t8T/4rvH4GOXWct4c 7fdfOhDFUlcXr1QaE22JLQ1DBRLdQQ9enkwjk0Ko= Subject: patch "serial: mvebu-uart: fix tx lost characters at power off" added to tty-linus To: pali@kernel.org, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Mon, 28 Dec 2020 16:17:51 +0100 Message-ID: <16091686718519@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled serial: mvebu-uart: fix tx lost characters at power off to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 54ca955b5a4024e2ce0f206b03adb7109bc4da26 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Pali=20Roh=C3=A1r?= Date: Wed, 23 Dec 2020 20:19:31 +0100 Subject: serial: mvebu-uart: fix tx lost characters at power off MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit c685af1108d7 ("serial: mvebu-uart: fix tx lost characters") fixed tx lost characters at low baud rates but started causing tx lost characters when kernel is going to power off or reboot. TX_EMP tells us when transmit queue is empty therefore all characters were transmitted. TX_RDY tells us when CPU can send a new character. Therefore we need to use different check prior transmitting new character and different check after all characters were sent. This patch splits polling code into two functions: wait_for_xmitr() which waits for TX_RDY and wait_for_xmite() which waits for TX_EMP. When rebooting A3720 platform without this patch on UART is print only: [ 42.699� And with this patch on UART is full output: [ 39.530216] reboot: Restarting system Fixes: c685af1108d7 ("serial: mvebu-uart: fix tx lost characters") Signed-off-by: Pali Rohár Cc: stable Link: https://lore.kernel.org/r/20201223191931.18343-1-pali@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/mvebu-uart.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c index 118b29912289..e0c00a1b0763 100644 --- a/drivers/tty/serial/mvebu-uart.c +++ b/drivers/tty/serial/mvebu-uart.c @@ -648,6 +648,14 @@ static void wait_for_xmitr(struct uart_port *port) (val & STAT_TX_RDY(port)), 1, 10000); } +static void wait_for_xmite(struct uart_port *port) +{ + u32 val; + + readl_poll_timeout_atomic(port->membase + UART_STAT, val, + (val & STAT_TX_EMP), 1, 10000); +} + static void mvebu_uart_console_putchar(struct uart_port *port, int ch) { wait_for_xmitr(port); @@ -675,7 +683,7 @@ static void mvebu_uart_console_write(struct console *co, const char *s, uart_console_write(port, s, count, mvebu_uart_console_putchar); - wait_for_xmitr(port); + wait_for_xmite(port); if (ier) writel(ier, port->membase + UART_CTRL(port)); -- 2.29.2