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authorAndres Salomon <dilinger@debian.org>2007-10-18 03:04:50 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-18 14:37:19 -0700
commit8f4ce8c32f2dc2bc2411cafe39976fc5c0adfabf (patch)
tree04f9009812e13f97b3eaae6385a0bb49cc2312b1
parent438e2ce68dfd4af4cfcec2f873564fb921db4bb5 (diff)
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: Andres Salomon <dilinger@debian.org> Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@suspend2.net> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/kernel-parameters.txt10
-rw-r--r--Documentation/power/basic-pm-debugging.txt4
-rw-r--r--arch/powerpc/configs/pmac32_defconfig1
-rw-r--r--drivers/serial/serial_core.c10
-rw-r--r--include/linux/console.h7
-rw-r--r--kernel/power/Kconfig11
-rw-r--r--kernel/printk.c16
7 files changed, 32 insertions, 27 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 98cf90f2631..189df0bcab9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -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>]
diff --git a/Documentation/power/basic-pm-debugging.txt b/Documentation/power/basic-pm-debugging.txt
index 1a85e2b964d..57aef2f6e0d 100644
--- a/Documentation/power/basic-pm-debugging.txt
+++ b/Documentation/power/basic-pm-debugging.txt
@@ -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
diff --git a/arch/powerpc/configs/pmac32_defconfig b/arch/powerpc/configs/pmac32_defconfig
index 95b823b60c9..8e5988c4a16 100644
--- a/arch/powerpc/configs/pmac32_defconfig
+++ b/arch/powerpc/configs/pmac32_defconfig
@@ -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
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 68aa4da0186..103189095c8 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -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);
diff --git a/include/linux/console.h b/include/linux/console.h
index 0a4542ddb73..a5f88a6a259 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -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);
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 14b0e10dc95..8e186c67814 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -44,17 +44,6 @@ config PM_VERBOSE
---help---
This option enables verbose messages from the Power Management code.
-config DISABLE_CONSOLE_SUSPEND
- bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
- depends on PM_DEBUG && PM_SLEEP
- default n
- ---help---
- This option turns off the console suspend mechanism that prevents
- debug messages from reaching the console during the suspend/resume
- operations. This may be helpful when debugging device drivers'
- suspend/resume routines, but may itself lead to problems, for example
- if netconsole is used.
-
config PM_TRACE
bool "Suspend/resume event tracing"
depends on PM_DEBUG && X86 && PM_SLEEP && EXPERIMENTAL
diff --git a/kernel/printk.c b/kernel/printk.c
index 52493474f0a..a30fe33de39 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -862,7 +862,16 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
return -1;
}
-#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
+int console_suspend_enabled = 1;
+EXPORT_SYMBOL(console_suspend_enabled);
+
+static int __init console_suspend_disable(char *str)
+{
+ console_suspend_enabled = 0;
+ return 1;
+}
+__setup("no_console_suspend", console_suspend_disable);
+
/**
* suspend_console - suspend the console subsystem
*
@@ -870,6 +879,8 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
*/
void suspend_console(void)
{
+ if (!console_suspend_enabled)
+ return;
printk("Suspending console(s)\n");
acquire_console_sem();
console_suspended = 1;
@@ -877,10 +888,11 @@ void suspend_console(void)
void resume_console(void)
{
+ if (!console_suspend_enabled)
+ return;
console_suspended = 0;
release_console_sem();
}
-#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */
/**
* acquire_console_sem - lock the console system for exclusive use.