[PATCH] swsusp: documentation updates

Update suspend-to-RAM documentation with new machines, and makes message
when processes can't be stopped little clearer.  (In one case, waiting
longer actually did help).

From: "Rafael J. Wysocki" <rjw@sisk.pl>

  Warn in the documentation that data may be lost if there are some
  filesystems mounted from USB devices before suspend.

  [Thanks to Alan Stern for providing the answer to the question in the
  Q:-A: part.]
Signed-off-by: NPavel Machek <pavel@suse.cz>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Documentation/power/swsusp.txt

@@ -17,6 +17,11 @@ Some warnings, first.
  * but it will probably only crash.
  *
  * (*) suspend/resume support is needed to make it safe.
+ *
+ * If you have any filesystems on USB devices mounted before suspend,
+ * they won't be accessible after resume and you may lose data, as though
+ * you have unplugged the USB devices with mounted filesystems on them
+ * (see the FAQ below for details).
 
 You need to append resume=/dev/your_swap_partition to kernel command
 line. Then you suspend by
@@ -27,19 +32,18 @@ echo shutdown > /sys/power/disk; echo disk > /sys/power/state
 
 echo platform > /sys/power/disk; echo disk > /sys/power/state
 
+. If you have SATA disks, you'll need recent kernels with SATA suspend
+support. For suspend and resume to work, make sure your disk drivers
+are built into kernel -- not modules. [There's way to make
+suspend/resume with modular disk drivers, see FAQ, but you probably
+should not do that.]
+
 If you want to limit the suspend image size to N bytes, do
 
 echo N > /sys/power/image_size
 
 before suspend (it is limited to 500 MB by default).
 
-Encrypted suspend image:
-------------------------
-If you want to store your suspend image encrypted with a temporary
-key to prevent data gathering after resume you must compile
-crypto and the aes algorithm into the kernel - modules won't work
-as they cannot be loaded at resume time.
-
 
 Article about goals and implementation of Software Suspend for Linux
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -333,4 +337,37 @@ init=/bin/bash, then swapon and starting suspend sequence manually
 usually does the trick. Then it is good idea to try with latest
 vanilla kernel.
 
+Q: How can distributions ship a swsusp-supporting kernel with modular
+disk drivers (especially SATA)?
+
+A: Well, it can be done, load the drivers, then do echo into
+/sys/power/disk/resume file from initrd. Be sure not to mount
+anything, not even read-only mount, or you are going to lose your
+data.
+
+Q: How do I make suspend more verbose?
+
+A: If you want to see any non-error kernel messages on the virtual
+terminal the kernel switches to during suspend, you have to set the
+kernel console loglevel to at least 5, for example by doing
+
+	echo 5 > /proc/sys/kernel/printk
+
+Q: Is this true that if I have a mounted filesystem on a USB device and
+I suspend to disk, I can lose data unless the filesystem has been mounted
+with "sync"?
+
+A: That's right.  It depends on your hardware, and it could be true even for
+suspend-to-RAM.  In fact, even with "-o sync" you can lose data if your
+programs have information in buffers they haven't written out to disk.
+
+If you're lucky, your hardware will support low-power modes for USB
+controllers while the system is asleep.  Lots of hardware doesn't,
+however.  Shutting off the power to a USB controller is equivalent to
+unplugging all the attached devices.
+
+Remember that it's always a bad idea to unplug a disk drive containing a
+mounted filesystem.  With USB that's true even when your system is asleep!
+The safest thing is to unmount all USB-based filesystems before suspending
+and remount them after resuming.
 

Documentation/power/video.txt

 
 		Video issues with S3 resume
 		~~~~~~~~~~~~~~~~~~~~~~~~~~~
-		  2003-2005, Pavel Machek
+		  2003-2006, Pavel Machek
 
 During S3 resume, hardware needs to be reinitialized. For most
 devices, this is easy, and kernel driver knows how to do
@@ -15,6 +15,27 @@ run normally so video card is normally initialized. It should not be
 problem for S1 standby, because hardware should retain its state over
 that.
 
+We either have to run video BIOS during early resume, or interpret it
+using vbetool later, or maybe nothing is neccessary on particular
+system because video state is preserved. Unfortunately different
+methods work on different systems, and no known method suits all of
+them.
+
+Userland application called s2ram has been developed; it contains long
+whitelist of systems, and automatically selects working method for a
+given system. It can be downloaded from CVS at
+www.sf.net/projects/suspend . If you get a system that is not in the
+whitelist, please try to find a working solution, and submit whitelist
+entry so that work does not need to be repeated.
+
+Currently, VBE_SAVE method (6 below) works on most
+systems. Unfortunately, vbetool only runs after userland is resumed,
+so it makes debugging of early resume problems
+hard/impossible. Methods that do not rely on userland are preferable.
+
+Details
+~~~~~~~
+
 There are a few types of systems where video works after S3 resume:
 
 (1) systems where video state is preserved over S3.
@@ -104,6 +125,7 @@ HP NX7000			??? (*)
 HP Pavilion ZD7000		vbetool post needed, need open-source nv driver for X
 HP Omnibook XE3	athlon version	none (1)
 HP Omnibook XE3GC		none (1), video is S3 Savage/IX-MV
+HP Omnibook 5150		none (1), (S1 also works OK)
 IBM TP T20, model 2647-44G	none (1), video is S3 Inc. 86C270-294 Savage/IX-MV, vesafb gets "interesting" but X work.
 IBM TP A31 / Type 2652-M5G      s3_mode (3) [works ok with BIOS 1.04 2002-08-23, but not at all with BIOS 1.11 2004-11-05 :-(]
 IBM TP R32 / Type 2658-MMG      none (1)
@@ -120,18 +142,24 @@ IBM ThinkPad T42p (2373-GTG)	s3_bios (2)
 IBM TP X20			??? (*)
 IBM TP X30			s3_bios (2)
 IBM TP X31 / Type 2672-XXH      none (1), use radeontool (http://fdd.com/software/radeon/) to turn off backlight.
-IBM TP X32			none (1), but backlight is on and video is trashed after long suspend
+IBM TP X32			none (1), but backlight is on and video is trashed after long suspend. s3_bios,s3_mode (4) works too. Perhaps that gets better results?
 IBM Thinkpad X40 Type 2371-7JG  s3_bios,s3_mode (4)
+IBM TP 600e			none(1), but a switch to console and back to X is needed
 Medion MD4220			??? (*)
 Samsung P35			vbetool needed (6)
-Sharp PC-AR10 (ATI rage)	none (1)
+Sharp PC-AR10 (ATI rage)	none (1), backlight does not switch off
 Sony Vaio PCG-C1VRX/K		s3_bios (2)
 Sony Vaio PCG-F403		??? (*)
+Sony Vaio PCG-GRT995MP		none (1), works with 'nv' X driver
+Sony Vaio PCG-GR7/K		none (1), but needs radeonfb, use radeontool (http://fdd.com/software/radeon/) to turn off backlight.
 Sony Vaio PCG-N505SN		??? (*)
 Sony Vaio vgn-s260		X or boot-radeon can init it (5)
+Sony Vaio vgn-S580BH		vga=normal, but suspend from X. Console will be blank unless you return to X.
+Sony Vaio vgn-FS115B		s3_bios (2),s3_mode (4)
 Toshiba Libretto L5		none (1)
-Toshiba Satellite 4030CDT	s3_mode (3)
-Toshiba Satellite 4080XCDT      s3_mode (3)
+Toshiba Portege 3020CT		s3_mode (3)
+Toshiba Satellite 4030CDT	s3_mode (3) (S1 also works OK)
+Toshiba Satellite 4080XCDT      s3_mode (3) (S1 also works OK)
 Toshiba Satellite 4090XCDT      ??? (*)
 Toshiba Satellite P10-554       s3_bios,s3_mode (4)(****)
 Toshiba M30                     (2) xor X with nvidia driver using internal AGP
@@ -151,39 +179,3 @@ Asus A7V8X	    nVidia RIVA TNT2 model 64	  s3_bios,s3_mode (4)
 (***) To be tested with a newer kernel.
 
 (****) Not with SMP kernel, UP only.
-
-VBEtool details
-~~~~~~~~~~~~~~~
-(with thanks to Carl-Daniel Hailfinger)
-
-First, boot into X and run the following script ONCE:
-#!/bin/bash
-statedir=/root/s3/state
-mkdir -p $statedir
-chvt 2
-sleep 1
-vbetool vbestate save >$statedir/vbe
-
-
-To suspend and resume properly, call the following script as root:
-#!/bin/bash
-statedir=/root/s3/state
-curcons=`fgconsole`
-fuser /dev/tty$curcons 2>/dev/null|xargs ps -o comm= -p|grep -q X && chvt 2
-cat /dev/vcsa >$statedir/vcsa
-sync
-echo 3 >/proc/acpi/sleep
-sync
-vbetool post
-vbetool vbestate restore <$statedir/vbe
-cat $statedir/vcsa >/dev/vcsa
-rckbd restart
-chvt $[curcons%6+1]
-chvt $curcons
-
-
-Unless you change your graphics card or other hardware configuration,
-the state once saved will be OK for every resume afterwards.
-NOTE: The "rckbd restart" command may be different for your
-distribution. Simply replace it with the command you would use to
-set the fonts on screen.

kernel/power/process.c

@@ -83,7 +83,7 @@ int freeze_processes(void)
 		yield();			/* Yield is okay here */
 		if (todo && time_after(jiffies, start_time + TIMEOUT)) {
 			printk( "\n" );
-			printk(KERN_ERR " stopping tasks failed (%d tasks remaining)\n", todo );
+			printk(KERN_ERR " stopping tasks timed out (%d tasks remaining)\n", todo );
 			break;
 		}
 	} while(todo);