linux-kernel - [PATCH RESEND] tty/serial/imx: Enable TXEN bit in imx_poll

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Message-Id: <20201201230307.5738-1-972931182@qq.com>
Date:   Wed,  2 Dec 2020 07:03:08 +0800
From:   jiladahe1997 <jiladahe1997@...il.com>
To:     gregkh@...uxfoundation.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de
Cc:     linux-imx@....com, linux-kernel@...r.kernel.org, 972931182@...com,
        Mingrui Ren <jiladahe1997@...il.com>
Subject: [PATCH RESEND] tty/serial/imx: Enable TXEN bit in imx_poll_init().

From: Mingrui Ren <jiladahe1997@...il.com>

As described in Documentation, poll_init() is called by kgdb to initialize
hardware which supports both poll_put_char() and poll_get_char().

It's necessary to enable TXEN bit, otherwise, it will cause hardware fault
and kernel panic when calling imx_poll_put_char().

Generally, if use /dev/ttymxc0 as kgdb console as well as system
console, ttymxc0 is initialized early by system console which does enable
TXEN bit.But when use /dev/ttymxc1 as kgbd console, ttymxc1 is only
initialized by imx_poll_init() cannot enable the TXEN bit, which will
cause kernel panic.

Signed-off-by: Mingrui Ren <jiladahe1997@...il.com>
---
Hi, thanks for your reply, and sorry for sending two identical emails.
The email service I used before seems to have some problems, 
so I switched to gmail.This is the "correct" version, please check.

 drivers/tty/serial/imx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 43c6d7142fdd..7c665db3d897 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1829,7 +1829,7 @@ static int imx_uart_poll_init(struct uart_port *port)
 	ucr1 |= UCR1_UARTEN;
 	ucr1 &= ~(UCR1_TRDYEN | UCR1_RTSDEN | UCR1_RRDYEN);

-	ucr2 |= UCR2_RXEN;
+	ucr2 |= UCR2_RXEN|UCR2_TXEN;
 	ucr2 &= ~UCR2_ATEN;

 	imx_uart_writel(sport, ucr1, UCR1);
-- 
2.29.2