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Date: Sun, 18 Oct 2009 17:46:40 +0200
From: Stanislav Brabec <utx@...guin.cz>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux@....linux.org.uk, linux-kernel@...r.kernel.org,
gregkh@...e.de, alan@...rguk.ukuu.org.uk, s.hauer@...gutronix.de,
saxena@...top.org, Pavel Machek <pavel@....cz>
Subject: Re: [PATCH] serial-core: resume serial hardware with
no_console_suspend
Attaching rebased patch.
Untested! (Explained in the previous mail.)
Also sending a "diff -w" on the same code in the next mail for easier
review.
-
BIOS-less devices may require hardware resume for proper work. It did
not happen with no_console_suspend (at least before ba15ab0e).
Perform a tricky suspend/resume with no_console_suspend.
Attempt to:
- 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
Signed-off-by: Stanislav Brabec <utx@...guin.cz>
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index dcc7244..f1e1ab2 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2008,12 +2008,6 @@ 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);
@@ -2021,20 +2015,23 @@ 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.
@@ -2049,16 +2046,18 @@ 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);
@@ -2075,29 +2074,6 @@ 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);
@@ -2123,21 +2099,23 @@ 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);
________________________________________________________________________
Stanislav Brabec
http://www.penguin.cz/~utx
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