linux-kernel - [PATCH 4.9 01/59] serial: mvebu-uart: Fix reporting of effective CSIZE to userspace

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Message-Id: <20181008175546.783325443@linuxfoundation.org>
Date:   Mon,  8 Oct 2018 20:31:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jan Kiszka <jan.kiszka@...mens.com>
Subject: [PATCH 4.9 01/59] serial: mvebu-uart: Fix reporting of effective CSIZE to userspace

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kiszka <jan.kiszka@...mens.com>

commit e0bf2d4982fe7d9ddaf550dd023803ea286f47fc upstream.

Apparently, this driver (or the hardware) does not support character
length settings. It's apparently running in 8-bit mode, but it makes
userspace believe it's in 5-bit mode. That makes tcsetattr with CS8
incorrectly fail, breaking e.g. getty from busybox, thus the login shell
on ttyMVx.

Fix by hard-wiring CS8 into c_cflag.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
Fixes: 30530791a7a0 ("serial: mvebu-uart: initial support for Armada-3700 serial port")
Cc: stable <stable@...r.kernel.org> # 4.6+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/serial/mvebu-uart.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -327,8 +327,10 @@ static void mvebu_uart_set_termios(struc
 	if ((termios->c_cflag & CREAD) == 0)
 		port->ignore_status_mask |= STAT_RX_RDY | STAT_BRK_ERR;
 
-	if (old)
+	if (old) {
 		tty_termios_copy_hw(termios, old);
+		termios->c_cflag |= CS8;
+	}
 
 	baud = uart_get_baud_rate(port, termios, old, 0, 460800);
 	uart_update_timeout(port, termios->c_cflag, baud);