From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.bootlin.com ([62.4.15.54]:47511 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752687AbeCOUW0 (ORCPT ); Thu, 15 Mar 2018 16:22:26 -0400 Date: Thu, 15 Mar 2018 21:21:37 +0100 From: Miquel Raynal To: Gabriel Matni Cc: "gregkh@linuxfoundation.org" , "linux-serial@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "stable@vger.kernel.org" , =?UTF-8?B?R3LDqWdvcnk=?= Clement , "Thomas Petazzoni" Subject: Re: [PATCH] serial: mvebu-uart: fix tx lost characters Message-ID: <20180315212137.57ca7c65@xps13> In-Reply-To: <3B588D51285A4A4D8D39C94212E078262787C0@SPQCMBX02.exfo.com> References: <3B588D51285A4A4D8D39C94212E078262748ED@SPQCMBX02.exfo.com> <20180315165516.GA9519@kroah.com> <3B588D51285A4A4D8D39C94212E078262787C0@SPQCMBX02.exfo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: stable-owner@vger.kernel.org List-ID: Hi Gabriel, On Thu, 15 Mar 2018 18:55:25 +0000, Gabriel Matni wrote: > From: Gabriel Matni > > 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 > > --- > drivers/tty/serial/mvebu-uart.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c > index a100e98259d7..400e1bc558b2 100644 > --- a/drivers/tty/serial/mvebu-uart.c > +++ b/drivers/tty/serial/mvebu-uart.c > @@ -618,7 +618,7 @@ static void wait_for_xmitr(struct uart_port *port) > u32 val; > > readl_poll_timeout_atomic(port->membase + UART_STAT, val, > - (val & STAT_TX_EMP), 1, 10000); > + (val & STAT_TX_RDY(port)), 1, 10000); I think this line should be indented like the one you replaced. Thanks, Miquèl -- Miquel Raynal, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com