From 18c9d4a3c249e9dcb1006bfd7d781616e152d77b Mon Sep 17 00:00:00 2001 From: Al Cooper Date: Thu, 24 Mar 2022 10:56:20 -0400 Subject: serial: When UART is suspended, set RTS to false When flow control is enabled, the UART should set RTS to false during suspend to stop incoming data. Currently, the suspend routine sets the mctrl register in the uart to zero, but leaves the shadow version in the uart_port struct alone so that resume can restore it. This causes a problem later in suspend when serial8250_do_shutdown() is called which uses the shadow mctrl register to clear some additional bits but ends up restoring RTS. The solution is to clear RTS from the shadow version before serial8250_do_shutdown() is called and restore it after. Signed-off-by: Al Cooper Link: https://lore.kernel.org/r/20220324145620.41573-1-alcooperx@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/tty/serial') diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 108b389e6e12..d067b44f1425 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2216,6 +2216,7 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) if (tty_port_initialized(port)) { const struct uart_ops *ops = uport->ops; int tries; + unsigned int mctrl; tty_port_set_suspended(port, 1); tty_port_set_initialized(port, 0); @@ -2223,6 +2224,9 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) spin_lock_irq(&uport->lock); ops->stop_tx(uport); ops->set_mctrl(uport, 0); + /* save mctrl so it can be restored on resume */ + mctrl = uport->mctrl; + uport->mctrl = 0; ops->stop_rx(uport); spin_unlock_irq(&uport->lock); @@ -2236,6 +2240,7 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) uport->name); ops->shutdown(uport); + uport->mctrl = mctrl; } /* -- cgit v1.2.3