Hibernation: prepare to enter the low power state
Rafael J. Wysocki [Thu, 19 Jul 2007 08:47:31 +0000 (01:47 -0700)]
During hibernation we call hibernation_ops->prepare() before creating the image,
but then, before saving it, we cancel the power transition by calling
hibernation_ops->finish().  Thus prior to calling hibernation_ops->enter() we
should let the platform firmware know that we're going to enter the low power
state after all.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/power/disk.c

index 77ac605..885c653 100644 (file)
@@ -205,12 +205,23 @@ int hibernation_restore(int platform_mode)
 
 int hibernation_platform_enter(void)
 {
+       int error;
+
        if (hibernation_ops) {
                kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
-               return hibernation_ops->enter();
+               /*
+                * We have cancelled the power transition by running
+                * hibernation_ops->finish() before saving the image, so we
+                * should let the firmware know that we're going to enter the
+                * sleep state after all
+                */
+               error = hibernation_ops->prepare();
+               if (!error)
+                       error = hibernation_ops->enter();
        } else {
-               return -ENOSYS;
+               error = -ENOSYS;
        }
+       return error;
 }
 
 /**