From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:54538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031576AbeEXKFW (ORCPT ); Thu, 24 May 2018 06:05:22 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miquel Raynal , Gregory CLEMENT , Gabriel Matni , Sasha Levin Subject: [PATCH 4.16 145/161] serial: mvebu-uart: fix tx lost characters Date: Thu, 24 May 2018 11:39:30 +0200 Message-Id: <20180524093035.718574153@linuxfoundation.org> In-Reply-To: <20180524093018.331893860@linuxfoundation.org> References: <20180524093018.331893860@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gabriel Matni [ Upstream commit c685af1108d7c303f0b901413405d68eaeac4477 ] Fixes missing characters on kernel console at low baud rates (i.e.9600). The driver should poll TX_RDY or TX_FIFO_EMP instead of TX_EMP to ensure that the transmitter holding register (THR) is ready to receive a new byte. TX_EMP tells us when it is possible to send a break sequence via SND_BRK_SEQ. While this also indicates that both the THR and the TSR are empty, it does not guarantee that a new byte can be written just yet. Fixes: 30530791a7a0 ("serial: mvebu-uart: initial support for Armada-3700 serial port") Reviewed-by: Miquel Raynal Acked-by: Gregory CLEMENT Signed-off-by: Gabriel Matni Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/mvebu-uart.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/serial/mvebu-uart.c +++ b/drivers/tty/serial/mvebu-uart.c @@ -617,7 +617,7 @@ static void wait_for_xmitr(struct uart_p u32 val; readl_poll_timeout_atomic(port->membase + UART_STAT, val, - (val & STAT_TX_EMP), 1, 10000); + (val & STAT_TX_RDY(port)), 1, 10000); } static void mvebu_uart_console_putchar(struct uart_port *port, int ch)