From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> 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 <geert+renesas@xxxxxxxxx> --- v2: - Drop serial console case, as this needs other fixes first 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 2cf5649a6dc0..0cec51ce8902 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1452,6 +1452,8 @@ 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); } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
