Latest working kernel version:
unknown or none
Earliest failing kernel version:
Earliest _tested_ by me failing kernel was 2.6.25
Debian 4.0, 5.0
IBM Thinkpad T21
IBM's special keys (Fn-X[*]) doesn't work after resume iff laptop is resumed on battery, without AC power connected.
[*] X can be
F4 - suspend to ram,
F7 - change video output (lcd, lcd+crt, crt),
F12 - suspend to disk.
This bug is special case of http://bugzilla.kernel.org/show_bug.cgi?id=11674
In this case special keys do work if suspend and resume is on AC power (without disconnecting AC in between).
Steps to reproduce:
1. Boot laptop on AC power
3. Disconnect AC power
I've just found that bug was already reported, it's not fixed yet -- bug confirmed in 2.6.29-rc7.
*** This bug has been marked as a duplicate of bug 10932 ***