PM: add kconfig option for deprecated .../power/state files

Add a new PM_SYSFS_DEPRECATED config option to control whether or
not the /sys/devices/.../power/state files are provided.  This will
make it easier to get rid of that mechanism when the time comes,
and to verify that userspace tools work right without it.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index e55b3c2..2d47517 100644 (file)
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -7,6 +7,8 @@
 #include "power.h"
 
 
+#ifdef CONFIG_PM_SYSFS_DEPRECATED
+
 /**
  *     state - Control current power state of device
  *
@@ -66,6 +68,8 @@ static ssize_t state_store(struct device * dev, struct device_attribute *attr, c
 static DEVICE_ATTR(state, 0644, state_show, state_store);
 
 
+#endif /* CONFIG_PM_SYSFS_DEPRECATED */
+
 /*
  *     wakeup - Report/change current wakeup option for device
  *
@@ -139,7 +143,9 @@ static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
 
 
 static struct attribute * power_attrs[] = {
+#ifdef CONFIG_PM_SYSFS_DEPRECATED
        &dev_attr_state.attr,
+#endif
        &dev_attr_wakeup.attr,
        NULL,
 };

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 619ecab..1ed9720 100644 (file)
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -53,6 +53,17 @@ config PM_TRACE
        CAUTION: this option will cause your machine's real-time clock to be
        set to an invalid time after a resume.
 
+config PM_SYSFS_DEPRECATED
+       bool "Driver model /sys/devices/.../power/state files (DEPRECATED)"
+       depends on PM && SYSFS
+       default n
+       help
+         The driver model started out with a sysfs file intended to provide
+         a userspace hook for device power management.  This feature has never
+         worked very well, except for limited testing purposes, and so it will
+         be removed.   It's not clear that a generic mechanism could really
+         handle the wide variability of device power states; any replacements
+         are likely to be bus or driver specific.
 
 config SOFTWARE_SUSPEND
        bool "Software Suspend"