linux-kernel - [PATCH] tty: serial: lpc32xx_hs: fix missing console boot messages

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Message-Id: <20190115171814.21789-1-alexandre.belloni@bootlin.com>
Date:   Tue, 15 Jan 2019 18:18:14 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vladimir Zapolskiy <vz@...ia.com>
Cc:     Sylvain Lemieux <slemieux.tyco@...il.com>,
        Roland Stigge <stigge@...com.de>, Jiri Slaby <jslaby@...e.com>,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH] tty: serial: lpc32xx_hs: fix missing console boot messages

When probing the HSUART, it is put in loopback mode in order to prevent a
potential issue that may happen on RX (Errata HSUART.1).

serial_lpc32xx_startup() moves it out of loopback mode but this is too late
to get the kernel boot messages before userspace opens the device.

Also get out of loopback mode in lpc32xx_hsuart_console_setup().

Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
 drivers/tty/serial/lpc32xx_hs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index d1d73261575b..f4e27d0ad947 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -151,6 +151,8 @@ static void lpc32xx_hsuart_console_write(struct console *co, const char *s,
 	local_irq_restore(flags);
 }
 
+static void lpc32xx_loopback_set(resource_size_t mapbase, int state);
+
 static int __init lpc32xx_hsuart_console_setup(struct console *co,
 					       char *options)
 {
@@ -170,6 +172,8 @@ static int __init lpc32xx_hsuart_console_setup(struct console *co,
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 
+	lpc32xx_loopback_set(port->mapbase, 0); /* get out of loopback mode */
+
 	return uart_set_options(port, co, baud, parity, bits, flow);
 }
 
-- 
2.20.1