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authorStanislav Brabec <sbrabec@suse.cz>2009-12-02 16:20:56 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2010-01-20 15:03:29 -0800
commit4547be7809a3b775ce750ec7f8b5748954741523 (patch)
treec4da7e9e0e461c42501299c355c03a9920ccdce6
parent6d34855d9aa281f72c533ecb827405139d1b0fe9 (diff)
downloadlinux-4547be7809a3b775ce750ec7f8b5748954741523.tar.gz
serial-core: resume serial hardware with no_console_suspend
Perform a tricky suspend/resume even with no_console_suspend. With no_console_suspend, kernel skips serial port suspend/resume and the serial hardware may remain in undefined state after resume. It actually happens on devices that don't have BIOS that handle serial initialization. It makes impossible to use serial console after resume. Devices affected by this problem include: Sharp Zaurus devices Several PXA based ARM embedded boards The patch does: - Save the hardware state - Perform buffer flush in time of its suspend call - Tell the driver that port is suspended - But still accept new data - And keep console hardware in state that allows to send them It allows to capture late console messages without breaking console after resume. This is just a resend of a patch discussed in these threads, as the patch was not yet applied. "Possible suspend/resume regression in .32-rc?" (Nov 1-5, 2009, ARM list, later LKML) "serial-core: resume serial hardware with no_console_suspend" (Sep 15-Oct 18, 2009, LKML & ARM lists) Signed-off-by: Stanislav Brabec <sbrabec@suse.cz> Tested-by: Haojian Zhuang <haojian.zhuang@gmail.com> Tested-by: Daniel Mack <daniel@caiaq.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/serial/serial_core.c88
1 files changed, 33 insertions, 55 deletions
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 047530b285b..fa4f170f2e8 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2006,12 +2006,6 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
mutex_lock(&port->mutex);
- if (!console_suspend_enabled && uart_console(uport)) {
- /* we're going to avoid suspending serial console */
- mutex_unlock(&port->mutex);
- return 0;
- }
-
tty_dev = device_find_child(uport->dev, &match, serial_match_port);
if (device_may_wakeup(tty_dev)) {
enable_irq_wake(uport->irq);
@@ -2019,20 +2013,23 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
mutex_unlock(&port->mutex);
return 0;
}
- uport->suspended = 1;
+ if (console_suspend_enabled || !uart_console(uport))
+ uport->suspended = 1;
if (port->flags & ASYNC_INITIALIZED) {
const struct uart_ops *ops = uport->ops;
int tries;
- set_bit(ASYNCB_SUSPENDED, &port->flags);
- clear_bit(ASYNCB_INITIALIZED, &port->flags);
+ if (console_suspend_enabled || !uart_console(uport)) {
+ set_bit(ASYNCB_SUSPENDED, &port->flags);
+ clear_bit(ASYNCB_INITIALIZED, &port->flags);
- spin_lock_irq(&uport->lock);
- ops->stop_tx(uport);
- ops->set_mctrl(uport, 0);
- ops->stop_rx(uport);
- spin_unlock_irq(&uport->lock);
+ spin_lock_irq(&uport->lock);
+ ops->stop_tx(uport);
+ ops->set_mctrl(uport, 0);
+ ops->stop_rx(uport);
+ spin_unlock_irq(&uport->lock);
+ }
/*
* Wait for the transmitter to empty.
@@ -2047,16 +2044,18 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
drv->dev_name,
drv->tty_driver->name_base + uport->line);
- ops->shutdown(uport);
+ if (console_suspend_enabled || !uart_console(uport))
+ ops->shutdown(uport);
}
/*
* Disable the console device before suspending.
*/
- if (uart_console(uport))
+ if (console_suspend_enabled && uart_console(uport))
console_stop(uport->cons);
- uart_change_pm(state, 3);
+ if (console_suspend_enabled || !uart_console(uport))
+ uart_change_pm(state, 3);
mutex_unlock(&port->mutex);
@@ -2073,29 +2072,6 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
mutex_lock(&port->mutex);
- if (!console_suspend_enabled && uart_console(uport)) {
- /* no need to resume serial console, it wasn't suspended */
- /*
- * First try to use the console cflag setting.
- */
- memset(&termios, 0, sizeof(struct ktermios));
- termios.c_cflag = uport->cons->cflag;
- /*
- * If that's unset, use the tty termios setting.
- */
- if (termios.c_cflag == 0)
- termios = *state->port.tty->termios;
- else {
- termios.c_ispeed = termios.c_ospeed =
- tty_termios_input_baud_rate(&termios);
- termios.c_ispeed = termios.c_ospeed =
- tty_termios_baud_rate(&termios);
- }
- uport->ops->set_termios(uport, &termios, NULL);
- mutex_unlock(&port->mutex);
- return 0;
- }
-
tty_dev = device_find_child(uport->dev, &match, serial_match_port);
if (!uport->suspended && device_may_wakeup(tty_dev)) {
disable_irq_wake(uport->irq);
@@ -2121,21 +2097,23 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
spin_lock_irq(&uport->lock);
ops->set_mctrl(uport, 0);
spin_unlock_irq(&uport->lock);
- ret = ops->startup(uport);
- if (ret == 0) {
- uart_change_speed(state, NULL);
- spin_lock_irq(&uport->lock);
- ops->set_mctrl(uport, uport->mctrl);
- ops->start_tx(uport);
- spin_unlock_irq(&uport->lock);
- set_bit(ASYNCB_INITIALIZED, &port->flags);
- } else {
- /*
- * Failed to resume - maybe hardware went away?
- * Clear the "initialized" flag so we won't try
- * to call the low level drivers shutdown method.
- */
- uart_shutdown(state);
+ if (console_suspend_enabled || !uart_console(uport)) {
+ ret = ops->startup(uport);
+ if (ret == 0) {
+ uart_change_speed(state, NULL);
+ spin_lock_irq(&uport->lock);
+ ops->set_mctrl(uport, uport->mctrl);
+ ops->start_tx(uport);
+ spin_unlock_irq(&uport->lock);
+ set_bit(ASYNCB_INITIALIZED, &port->flags);
+ } else {
+ /*
+ * Failed to resume - maybe hardware went away?
+ * Clear the "initialized" flag so we won't try
+ * to call the low level drivers shutdown method.
+ */
+ uart_shutdown(state);
+ }
}
clear_bit(ASYNCB_SUSPENDED, &port->flags);