Commit 8f4ce8c3 authored by Andres Salomon's avatar Andres Salomon Committed by Linus Torvalds
Browse files

serial: turn serial console suspend a boot rather than compile time option 



Currently, there's a CONFIG_DISABLE_CONSOLE_SUSPEND that allows one to stop
the serial console from being suspended when the rest of the machine goes
to sleep.  This is incredibly useful for debugging power management-related
things; however, having it as a compile-time option has proved to be
incredibly inconvenient for us (OLPC).  There are plenty of times that we
want serial console to not suspend, but for the most part we'd like serial
console to be suspended.

This drops CONFIG_DISABLE_CONSOLE_SUSPEND, and replaces it with a kernel
boot parameter (no_console_suspend).  By default, the serial console will
be suspended along with the rest of the system; by passing
'no_console_suspend' to the kernel during boot, serial console will remain
alive during suspend.

For now, this is pretty serial console specific; further fixes could be
applied to make this work for things like netconsole.

Signed-off-by: default avatarAndres Salomon <dilinger@debian.org>
Acked-by: default avatar"Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@suspend2.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 438e2ce6

Documentation/kernel-parameters.txt

+10 −0
Original line number Diff line number Diff line
@@ -479,6 +479,16 @@ and is between 256 and 4096 characters. It is defined in the file 
			UART at the specified I/O port or MMIO address.

			The options are the same as for ttyS, above.



	no_console_suspend

			[HW] Never suspend the console

			Disable suspending of consoles during suspend and

			hibernate operations.  Once disabled, debugging

			messages can reach various consoles while the rest

			of the system is being put to sleep (ie, while

			debugging driver suspend/resume hooks).  This may

			not work reliably with all consoles, but is known

			to work with serial and VGA consoles.



	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver

			Format:

			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

Documentation/power/basic-pm-debugging.txt

+2 −2
Original line number Diff line number Diff line
@@ -78,8 +78,8 @@ c) Advanced debugging 
In case the STD does not work on your system even in the minimal configuration

and compiling more drivers as modules is not practical or some modules cannot

be unloaded, you can use one of the more advanced debugging techniques to find

the problem.  First, if there is a serial port in your box, you can set the

CONFIG_DISABLE_CONSOLE_SUSPEND kernel configuration option and try to log kernel

the problem.  First, if there is a serial port in your box, you can boot the

kernel with the 'no_console_suspend' parameter and try to log kernel

messages using the serial console.  This may provide you with some information

about the reasons of the suspend (resume) failure.  Alternatively, it may be

possible to use a FireWire port for debugging with firescope

arch/powerpc/configs/pmac32_defconfig

+0 −1
Original line number Diff line number Diff line
@@ -209,7 +209,6 @@ CONFIG_PM=y 
# CONFIG_PM_LEGACY is not set

CONFIG_PM_DEBUG=y

# CONFIG_PM_VERBOSE is not set

# CONFIG_DISABLE_CONSOLE_SUSPEND is not set

CONFIG_PM_SLEEP=y

CONFIG_SUSPEND=y

CONFIG_HIBERNATION=y

drivers/serial/serial_core.c

+4 −6
Original line number Diff line number Diff line
@@ -1959,12 +1959,11 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port) 


	mutex_lock(&state->mutex);



#ifdef CONFIG_DISABLE_CONSOLE_SUSPEND

	if (uart_console(port)) {

	if (!console_suspend_enabled && uart_console(port)) {

		/* we're going to avoid suspending serial console */

		mutex_unlock(&state->mutex);

		return 0;

	}

#endif



	tty_dev = device_find_child(port->dev, &match, serial_match_port);

	if (device_may_wakeup(tty_dev)) {
@@ -2016,12 +2015,11 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port) 


	mutex_lock(&state->mutex);



#ifdef CONFIG_DISABLE_CONSOLE_SUSPEND

	if (uart_console(port)) {

	if (!console_suspend_enabled && uart_console(port)) {

		/* no need to resume serial console, it wasn't suspended */

		mutex_unlock(&state->mutex);

		return 0;

	}

#endif



	if (!port->suspended) {

		disable_irq_wake(port->irq);

include/linux/console.h

+2 −5
Original line number Diff line number Diff line
@@ -122,14 +122,11 @@ extern void console_stop(struct console *); 
extern void console_start(struct console *);

extern int is_console_locked(void);



#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND

extern int console_suspend_enabled;



/* Suspend and resume console messages over PM events */

extern void suspend_console(void);

extern void resume_console(void);

#else

static inline void suspend_console(void) {}

static inline void resume_console(void) {}

#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */



int mda_console_init(void);

void prom_con_init(void);

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