diff options
author | Pavel Machek <pavel@ucw.cz> | 2006-12-06 20:34:46 -0800 |
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committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-07 08:39:28 -0800 |
commit | 06df6a5c181f462c71ddcc20ff6c7ea0bec18ec8 (patch) | |
tree | d5cadf44380e75d16f11117c65a848f1a6cdd204 /Documentation/power/s2ram.txt | |
parent | 59a493350e7aefff7e262efa39e017517b31b8e8 (diff) | |
download | linux-06df6a5c181f462c71ddcc20ff6c7ea0bec18ec8.tar.bz2 |
[PATCH] s2ram debugging documentation
Linus posted quite nice TRACE_RESUME how-to, and I think it is too nice to
be hidden in archives of mailing list, so I turned it into Documentation
piece.
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/power/s2ram.txt')
-rw-r--r-- | Documentation/power/s2ram.txt | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/Documentation/power/s2ram.txt b/Documentation/power/s2ram.txt new file mode 100644 index 000000000000..b05f512130ea --- /dev/null +++ b/Documentation/power/s2ram.txt @@ -0,0 +1,56 @@ + How to get s2ram working + ~~~~~~~~~~~~~~~~~~~~~~~~ + 2006 Linus Torvalds + 2006 Pavel Machek + +1) Check suspend.sf.net, program s2ram there has long whitelist of + "known ok" machines, along with tricks to use on each one. + +2) If that does not help, try reading tricks.txt and + video.txt. Perhaps problem is as simple as broken module, and + simple module unload can fix it. + +3) You can use Linus' TRACE_RESUME infrastructure, described below. + + Using TRACE_RESUME + ~~~~~~~~~~~~~~~~~~ + +I've been working at making the machines I have able to STR, and almost +always it's a driver that is buggy. Thank God for the suspend/resume +debugging - the thing that Chuck tried to disable. That's often the _only_ +way to debug these things, and it's actually pretty powerful (but +time-consuming - having to insert TRACE_RESUME() markers into the device +driver that doesn't resume and recompile and reboot). + +Anyway, the way to debug this for people who are interested (have a +machine that doesn't boot) is: + + - enable PM_DEBUG, and PM_TRACE + + - use a script like this: + + #!/bin/sh + sync + echo 1 > /sys/power/pm_trace + echo mem > /sys/power/state + + to suspend + + - if it doesn't come back up (which is usually the problem), reboot by + holding the power button down, and look at the dmesg output for things + like + + Magic number: 4:156:725 + hash matches drivers/base/power/resume.c:28 + hash matches device 0000:01:00.0 + + which means that the last trace event was just before trying to resume + device 0000:01:00.0. Then figure out what driver is controlling that + device (lspci and /sys/devices/pci* is your friend), and see if you can + fix it, disable it, or trace into its resume function. + +For example, the above happens to be the VGA device on my EVO, which I +used to run with "radeonfb" (it's an ATI Radeon mobility). It turns out +that "radeonfb" simply cannot resume that device - it tries to set the +PLL's, and it just _hangs_. Using the regular VGA console and letting X +resume it instead works fine. |