power management: remove firmware disk mode

This patch removes the firmware disk suspend mode which is the wrong approach,
it is supposed to be used for implementing firmware-based disk suspend but
cannot actually be used for that.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: <linux-pm@lists.linux-foundation.org>
Cc: David Brownell <david-b@pacbell.net>
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>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/power/interface.txt

@@ -18,17 +18,10 @@ states.
 
 
 /sys/power/disk controls the operating mode of the suspend-to-disk
-mechanism. Suspend-to-disk can be handled in several ways. The
-greatest distinction is who writes memory to disk - the firmware or
-the kernel. If the firmware does it, we assume that it also handles
-suspending the system. 
-
-If the kernel does it, then we have three options for putting the system
-to sleep - using the platform driver (e.g. ACPI or other PM
-registers), powering off the system or rebooting the system (for
-testing). The system will support either 'firmware' or 'platform', and
-that is known a priori. But, the user may choose 'shutdown' or
-'reboot' as alternatives. 
+mechanism. Suspend-to-disk can be handled in several ways. We have a
+few options for putting the system to sleep - using the platform driver
+(e.g. ACPI or other pm_ops), powering off the system or rebooting the
+system (for testing).
 
 Additionally, /sys/power/disk can be used to turn on one of the two testing
 modes of the suspend-to-disk mechanism: 'testproc' or 'test'.  If the
@@ -44,16 +37,12 @@ is being slow and which device drivers are misbehaving.
 Reading from this file will display what the mode is currently set
 to. Writing to this file will accept one of
 
-       'firmware'
-       'platform'
+       'platform' (only if the platform supports it)
        'shutdown'
        'reboot'
        'testproc'
        'test'
 
-It will only change to 'firmware' or 'platform' if the system supports
-it. 
-
 /sys/power/image_size controls the size of the image created by
 the suspend-to-disk mechanism.  It can be written a string
 representing a non-negative integer that will be used as an upper

Documentation/power/states.txt

@@ -62,17 +62,18 @@ setup via another operating system for it to use. Despite the
 inconvenience, this method requires minimal work by the kernel, since
 the firmware will also handle restoring memory contents on resume. 
 
-If the kernel is responsible for persistently saving state, a mechanism
-called 'swsusp' (Swap Suspend) is used to write memory contents to
-free swap space. swsusp has some restrictive requirements, but should
-work in most cases. Some, albeit outdated, documentation can be found
-in Documentation/power/swsusp.txt. 
+For suspend-to-disk, a mechanism called swsusp called 'swsusp' (Swap
+Suspend) is used to write memory contents to free swap space.
+swsusp has some restrictive requirements, but should work in most
+cases. Some, albeit outdated, documentation can be found in
+Documentation/power/swsusp.txt. Alternatively, userspace can do most
+of the actual suspend to disk work, see userland-swsusp.txt.
 
 Once memory state is written to disk, the system may either enter a
 low-power state (like ACPI S4), or it may simply power down. Powering
 down offers greater savings, and allows this mechanism to work on any
 system. However, entering a real low-power state allows the user to
-trigger wake up events (e.g. pressing a key or opening a laptop lid). 
+trigger wake up events (e.g. pressing a key or opening a laptop lid).
 
 A transition from Suspend-to-Disk to the On state should take about 30
 seconds, though it's typically a bit more with the current

Documentation/power/swsusp.txt

@@ -156,8 +156,7 @@ instead set the PF_NOFREEZE process flag when creating the thread (and
 be very careful).
 
 
-Q: What is the difference between "platform", "shutdown" and
-"firmware" in /sys/power/disk?
+Q: What is the difference between "platform" and "shutdown"?
 
 A:
 
@@ -166,11 +165,8 @@ shutdown: save state in linux, then tell bios to powerdown
 platform: save state in linux, then tell bios to powerdown and blink
           "suspended led"
 
-firmware: tell bios to save state itself [needs BIOS-specific suspend
-	  partition, and has very little to do with swsusp]
-
-"platform" is actually right thing to do, but "shutdown" is most
-reliable.
+"platform" is actually right thing to do where supported, but
+"shutdown" is most reliable (except on ACPI systems).
 
 Q: I do not understand why you have such strong objections to idea of
 selective suspend.
@@ -388,8 +384,8 @@ while the system is asleep, maintaining the connection, using true sleep
 modes like "suspend-to-RAM" or "standby".  (Don't write "disk" to the
 /sys/power/state file; write "standby" or "mem".)  We've not seen any
 hardware that can use these modes through software suspend, although in
-theory some systems might support "platform" or "firmware" modes that
-won't break the USB connections.
+theory some systems might support "platform" modes that won't break the
+USB connections.
 
 Remember that it's always a bad idea to unplug a disk drive containing a
 mounted filesystem.  That's true even when your system is asleep!  The

include/linux/pm.h

@@ -114,13 +114,12 @@ 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)
-#define	PM_DISK_REBOOT		((__force suspend_disk_method_t) 4)
-#define	PM_DISK_TEST		((__force suspend_disk_method_t) 5)
-#define	PM_DISK_TESTPROC	((__force suspend_disk_method_t) 6)
-#define	PM_DISK_MAX		((__force suspend_disk_method_t) 7)
+#define	PM_DISK_PLATFORM	((__force suspend_disk_method_t) 1)
+#define	PM_DISK_SHUTDOWN	((__force suspend_disk_method_t) 2)
+#define	PM_DISK_REBOOT		((__force suspend_disk_method_t) 3)
+#define	PM_DISK_TEST		((__force suspend_disk_method_t) 4)
+#define	PM_DISK_TESTPROC	((__force suspend_disk_method_t) 5)
+#define	PM_DISK_MAX		((__force suspend_disk_method_t) 6)
 
 /**
  * struct pm_ops - Callbacks for managing platform dependent suspend states.

kernel/power/disk.c

@@ -122,8 +122,6 @@ static int prepare_processes(void)
 /**
  *	pm_suspend_disk - The granpappy of hibernation power management.
  *
- *	If we're going through the firmware, then get it over with quickly.
- *
  *	If not, then call swsusp to do its thing, then figure out how
  *	to power down the system.
  */
@@ -292,7 +290,6 @@ late_initcall(software_resume);
 
 
 static const char * const pm_disk_modes[] = {
-	[PM_DISK_FIRMWARE]	= "firmware",
 	[PM_DISK_PLATFORM]	= "platform",
 	[PM_DISK_SHUTDOWN]	= "shutdown",
 	[PM_DISK_REBOOT]	= "reboot",
@@ -303,27 +300,25 @@ static const char * const pm_disk_modes[] = {
 /**
  *	disk - Control suspend-to-disk mode
  *
- *	Suspend-to-disk can be handled in several ways. The greatest
- *	distinction is who writes memory to disk - the firmware or the OS.
- *	If the firmware does it, we assume that it also handles suspending
- *	the system.
- *	If the OS does it, then we have three options for putting the system
- *	to sleep - using the platform driver (e.g. ACPI or other PM registers),
- *	powering off the system or rebooting the system (for testing).
+ *	Suspend-to-disk can be handled in several ways. We have a few options
+ *	for putting the system to sleep - using the platform driver (e.g. ACPI
+ *	or other pm_ops), powering off the system or rebooting the system
+ *	(for testing) as well as the two test modes.
  *
- *	The system will support either 'firmware' or 'platform', and that is
- *	known a priori (and encoded in pm_ops). But, the user may choose
- *	'shutdown' or 'reboot' as alternatives.
+ *	The system can support 'platform', and that is known a priori (and
+ *	encoded in pm_ops). However, the user may choose 'shutdown' or 'reboot'
+ *	as alternatives, as well as the test modes 'test' and 'testproc'.
  *
  *	show() will display what the mode is currently set to.
  *	store() will accept one of
  *
- *	'firmware'
  *	'platform'
  *	'shutdown'
  *	'reboot'
+ *	'test'
+ *	'testproc'
  *
- *	It will only change to 'firmware' or 'platform' if the system
+ *	It will only change to 'platform' if the system
  *	supports it (as determined from pm_ops->pm_disk_mode).
  */
 
@@ -345,7 +340,7 @@ static ssize_t disk_store(struct subsystem * s, const char * buf, size_t n)
 	len = p ? p - buf : n;
 
 	mutex_lock(&pm_mutex);
-	for (i = PM_DISK_FIRMWARE; i < PM_DISK_MAX; i++) {
+	for (i = PM_DISK_PLATFORM; i < PM_DISK_MAX; i++) {
 		if (!strncmp(buf, pm_disk_modes[i], len)) {
 			mode = i;
 			break;