path: root/Documentation/power
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authorJames Hogan <james@albanarts.com>2010-10-12 00:00:25 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2010-10-17 01:57:50 +0200
commitd33ac60beaf2c7dee5cd90aba7c1eb385dd70937 (patch)
tree7393c5f323433f39d2c64e7d9990aa7565397214 /Documentation/power
parent2ac21c6bc4249ee6d922f18dbec7266377592c32 (diff)
PM: Add sysfs attr for rechecking dev hash from PM trace
If the device which fails to resume is part of a loadable kernel module it won't be checked at startup against the magic number stored in the RTC. Add a read-only sysfs attribute /sys/power/pm_trace_dev_match which contains a list of newline separated devices (usually just the one) which currently match the last magic number. This allows the device which is failing to resume to be found after the modules are loaded again. Signed-off-by: James Hogan <james@albanarts.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'Documentation/power')
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/power/s2ram.txt b/Documentation/power/s2ram.txt
index 514b94fc931e..1bdfa0443773 100644
--- a/Documentation/power/s2ram.txt
+++ b/Documentation/power/s2ram.txt
@@ -49,6 +49,13 @@ machine that doesn't boot) is:
device (lspci and /sys/devices/pci* is your friend), and see if you can
fix it, disable it, or trace into its resume function.
+ If no device matches the hash (or any matches appear to be false positives),
+ the culprit may be a device from a loadable kernel module that is not loaded
+ until after the hash is checked. You can check the hash against the current
+ devices again after more modules are loaded using sysfs:
+ cat /sys/power/pm_trace_dev_match
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