From bf903c0c6ddfedec19ba92626ca30e98bfafbe08 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Thu, 27 Mar 2014 11:40:39 +0100 Subject: [PATCH] serial_core: Fix pm imbalance on unbind When a serial port is closed, uart_close() takes care of shutting down the hardware, and powering it down. When a serial port is unbound while in use, uart_close() bypasses all of this, as this is supposed to be done through uart_hangup() (invoked via tty_vhangup() in uart_remove_one_port()). However, uart_hangup() does not set the hardware's power state, leaving it powered up. This may also lead to unbounded nesting counts in clock and power management, depending on their internal implementation. Make sure to power down the port in uart_hangup(), except when the port is used as a serial console. For serial consoles, this operation must be postponed until after the port becomes completely unused. This case is not fixed yet, as it depends on a (future) fix for the tty->count vs. port->count imbalance on failed uart_open(). After this, the module clock used by the sh-sci driver is disabled on unbind while the serial port is in use. Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index dd1a7bef6647..f26834d262b3 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1451,6 +1451,8 @@ static void uart_hangup(struct tty_struct *tty) clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags); spin_unlock_irqrestore(&port->lock, flags); tty_port_tty_set(port, NULL); + if (!uart_console(state->uart_port)) + uart_change_pm(state, UART_PM_STATE_OFF); wake_up_interruptible(&port->open_wait); wake_up_interruptible(&port->delta_msr_wait); } -- 2.34.1