linux-kernel - [PATCH 4.18 137/228] serial: mvebu-uart: Fix reporting of effective CSIZE to userspace

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Date:   Tue,  2 Oct 2018 06:23:54 -0700
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 4.18 137/228] serial: mvebu-uart: Fix reporting of effective CSIZE to userspace

4.18-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 |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -511,6 +511,7 @@ static void mvebu_uart_set_termios(struc
 		termios->c_iflag |= old->c_iflag & ~(INPCK | IGNPAR);
 		termios->c_cflag &= CREAD | CBAUD;
 		termios->c_cflag |= old->c_cflag & ~(CREAD | CBAUD);
+		termios->c_cflag |= CS8;
 	}
 
 	spin_unlock_irqrestore(&port->lock, flags);