4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Fabio Estevam <fabio.estevam@xxxxxxx> commit 38b1f0fb42f772b8c9aac53593883a18ff5eb9d7 upstream. The wakeup mechanism via RTSDEN bit relies on the system using the RTS/CTS lines, so only allow such wakeup method when the system actually has RTS/CTS support. Fixes: bc85734b126f ("serial: imx: allow waking up on RTSD") Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxx> Reviewed-by: Martin Kaiser <martin@xxxxxxxxx> Acked-by: Fugang Duan <fugang.duan@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/serial/imx.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -2057,12 +2057,14 @@ static void serial_imx_enable_wakeup(str val &= ~UCR3_AWAKEN; writel(val, sport->port.membase + UCR3); - val = readl(sport->port.membase + UCR1); - if (on) - val |= UCR1_RTSDEN; - else - val &= ~UCR1_RTSDEN; - writel(val, sport->port.membase + UCR1); + if (sport->have_rtscts) { + val = readl(sport->port.membase + UCR1); + if (on) + val |= UCR1_RTSDEN; + else + val &= ~UCR1_RTSDEN; + writel(val, sport->port.membase + UCR1); + } } static int imx_serial_port_suspend_noirq(struct device *dev)