From 773598357c0baf03081cf87f2b444f97744faf1e Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Thu, 19 Jan 2012 11:28:56 -0800 Subject: serial: Fix wakeup init logic to speed up startup The synchronize_rcu() call resulting from making every serial driver wake-up capable (commit b3b708fa) slows boot down on my Tegra2x system (with CONFIG_PREEMPT disabled). But this is avoidable since it is the device_set_wakeup_enable() and then subsequence disable which causes the delay. We might as well just make the device wakeup capable but not actually enable it for wakeup until needed. Effectively the current code does this: device_set_wakeup_capable(dev, 1); device_set_wakeup_enable(dev, 1); device_set_wakeup_enable(dev, 0); We can just drop the last two lines. Before this change my boot log says: [ 0.227062] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled [ 0.702928] serial8250.0: ttyS0 at MMIO 0x70006040 (irq = 69) is a Tegra after: [ 0.227264] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled [ 0.227983] serial8250.0: ttyS0 at MMIO 0x70006040 (irq = 69) is a Tegra for saving of 450ms. Suggested-by: Rafael J. Wysocki Acked-by: Rafael J. Wysocki Signed-off-by: Simon Glass Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index c7bf31a6a7e..13056180adf 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2348,11 +2348,11 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport) */ tty_dev = tty_register_device(drv->tty_driver, uport->line, uport->dev); if (likely(!IS_ERR(tty_dev))) { - device_init_wakeup(tty_dev, 1); - device_set_wakeup_enable(tty_dev, 0); - } else + device_set_wakeup_capable(tty_dev, 1); + } else { printk(KERN_ERR "Cannot register tty device on line %d\n", uport->line); + } /* * Ensure UPF_DEAD is not set. -- cgit v1.2.3