serial: core: Preserve termios c_cflag for console resume

commit ae84db9661cafc63d179e1d985a2c5b841ff0ac4 upstream.

When a tty is opened for the serial console, the termios c_cflag
settings are inherited from the console line settings.
However, if the tty is subsequently closed, the termios settings
are lost. This results in a garbled console if the console is later
suspended and resumed.

Preserve the termios c_cflag for the serial console when the tty
is shutdown; this reflects the most recent line settings.

Fixes: Bugzilla #69751, 'serial console does not wake from S3'
Reported-by: Valerio Vanni <valerio.vanni@inwind.it>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index ece2049..25b8f68 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -235,6 +235,9 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
                /*
                 * Turn off DTR and RTS early.
                 */
+               if (uart_console(uport) && tty)
+                       uport->cons->cflag = tty->termios.c_cflag;
+
                if (!tty || (tty->termios.c_cflag & HUPCL))
                        uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);