[PATCH V2] printk:add console_suspend module parameter

[Yanmin Zhang <yanmin_zhang@linux.intel.com>]

We are enabling some power features on medfield. To test suspend-2-RAM
conveniently, we need turn on/off console_suspend_enabled frequently.

Below patch adds a module parameter, so users could change it by:
/sys/module/printk/parameters/console_suspend

Signed-off-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>

---

 Documentation/kernel-parameters.txt |    5 +++++
 kernel/printk.c                     |    4 ++++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 614d038..74446e0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1642,6 +1642,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			debugging driver suspend/resume hooks).  This may
 			not work reliably with all consoles, but is known
 			to work with serial and VGA consoles.
+			To facilitate more flexible debugging, we also add
+			console_suspend, a printk module parameter to control
+			it. Users could use console_suspend (usually
+			/sys/module/printk/parameters/console_suspend) to
+			turn on/off it dynamically.
 
 	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
 			caches in the slab allocator.  Saves per-node memory,
diff --git a/kernel/printk.c b/kernel/printk.c
index 836a2ae..b9ef93a 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1108,6 +1108,10 @@ static int __init console_suspend_disable(char *str)
 	return 1;
 }
 __setup("no_console_suspend", console_suspend_disable);
+module_param_named(console_suspend, console_suspend_enabled,
+		bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
+	" and hibernate operations");
 
 /**
  * suspend_console - suspend the console subsystem
-- 
1.7.1