rework pm_ops pm_disk_mode, kill misuse
This patch series cleans up some misconceptions about pm_ops. Some users of
the pm_ops structure attempt to use it to stop the user from entering suspend
to disk, this, however, is not possible since the user can always use
"shutdown" in /sys/power/disk and then the pm_ops are never invoked. Also,
platforms that don't support suspend to disk simply should not allow
configuring SOFTWARE_SUSPEND (read the help text on it, it only selects
suspend to disk and nothing else, all the other stuff depends on PM).
The pm_ops structure is actually intended to provide a way to enter
platform-defined sleep states (currently supported states are "standby" and
"mem" (suspend to ram)) and additionally (if SOFTWARE_SUSPEND is configured)
allows a platform to support a platform specific way to enter low-power mode
once everything has been saved to disk. This is currently only used by ACPI
(S4).
This patch:
The pm_ops.pm_disk_mode is used in totally bogus ways since nobody really
seems to understand what it actually does.
This patch clarifies the pm_disk_mode description.
It also removes all the arm and sh users that think they can veto suspend to
disk via pm_ops; not so since the user can always do echo shutdown >
/sys/power/disk, they need to find a better way involving Kconfig or such.
ACPI is the only user left with a non-zero pm_disk_mode.
The patch also sets the default mode to shutdown again, but when a new pm_ops
is registered its pm_disk_mode is selected as default, that way the default
stays for ACPI where it is apparently required.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: David Brownell <david-b@pacbell.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: <linux-pm@lists.linux-foundation.org>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 9bd86db..dfced91 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -112,6 +112,8 @@
typedef int __bitwise suspend_disk_method_t;
+/* invalid must be 0 so struct pm_ops initialisers can leave it out */
+#define PM_DISK_INVALID ((__force suspend_disk_method_t) 0)
#define PM_DISK_FIRMWARE ((__force suspend_disk_method_t) 1)
#define PM_DISK_PLATFORM ((__force suspend_disk_method_t) 2)
#define PM_DISK_SHUTDOWN ((__force suspend_disk_method_t) 3)
@@ -137,17 +139,16 @@
* @finish: Called when the system has left the given state and all devices
* are resumed. The return value is ignored.
*
- * @pm_disk_mode: Set to the disk method that the user should be able to
- * configure for suspend-to-disk. Since %PM_DISK_SHUTDOWN,
- * %PM_DISK_REBOOT, %PM_DISK_TEST and %PM_DISK_TESTPROC
- * are always allowed, currently only %PM_DISK_PLATFORM
- * makes sense. If the user then choses %PM_DISK_PLATFORM,
- * the @prepare call will be called before suspending to disk
- * (if present), the @enter call should be present and will
- * be called after all state has been saved and the machine
- * is ready to be shut down/suspended/..., and the @finish
- * callback is called after state has been restored. All
- * these calls are called with %PM_SUSPEND_DISK as the state.
+ * @pm_disk_mode: The generic code always allows one of the shutdown methods
+ * %PM_DISK_SHUTDOWN, %PM_DISK_REBOOT, %PM_DISK_TEST and
+ * %PM_DISK_TESTPROC. If this variable is set, the mode it is set
+ * to is allowed in addition to those modes and is also made default.
+ * When this mode is sent selected, the @prepare call will be called
+ * before suspending to disk (if present), the @enter call should be
+ * present and will be called after all state has been saved and the
+ * machine is ready to be powered off; the @finish callback is called
+ * after state has been restored. All these calls are called with
+ * %PM_SUSPEND_DISK as the state.
*/
struct pm_ops {
int (*valid)(suspend_state_t state);