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>

1 files changed, 0 insertions, 9 deletions

diff --git a/arch/arm/plat-s3c24xx/pm.c b/arch/arm/plat-s3c24xx/pm.c
index ecf68d611904..d6af3082af30 100644
--- a/arch/arm/plat-s3c24xx/pm.c
+++ b/arch/arm/plat-s3c24xx/pm.c
@@ -511,11 +511,6 @@ static int s3c2410_pm_enter(suspend_state_t state)
                 return -EINVAL;
         }
 
-        if (state != PM_SUSPEND_MEM) {
-                printk(KERN_ERR PFX "error: only PM_SUSPEND_MEM supported\n");
-                return -EINVAL;
-        }
-
         /* check if we have anything to wake-up with... bad things seem
          * to happen if you suspend with no wakeup (system will often
          * require a full power-cycle)
@@ -633,11 +628,7 @@ static int s3c2410_pm_finish(suspend_state_t state)
         return 0;
 }
 
-/*
- * Set to PM_DISK_FIRMWARE so we can quickly veto suspend-to-disk.
- */
 static struct pm_ops s3c2410_pm_ops = {
-        .pm_disk_mode   = PM_DISK_FIRMWARE,
         .prepare        = s3c2410_pm_prepare,
         .enter          = s3c2410_pm_enter,
         .finish         = s3c2410_pm_finish,