Machine shutdown after resume from S3

[Herton Ronaldo Krzesinski <herton@mandriva.com.br>]

I have here an Intel Classmate hardware sample, and I have a weird problem 
with suspend to ram, the machine does a power off when resuming.

I isolated the problem to the button acpi module, without loading it (or just 
removing it before doing a s2ram) I don't get the problem. In the specific 
machine I have here I can only resume it pressing the power button, so I 
think this is related.

I started looking into the kernel code and did some tests. The first thing I 
tried just as a test was to disable the code in acpi_button_notify function. 
As expected it stopped to send the power button key events 
to /proc/acpi/event, but I still got the same s2ram issues. But if I disable 
acpi_install_fixed_event_handler calls in acpi_button_install_notify_handlers 
the power off issue in s2ram was gone, of course also with power button not
notifying anything anymore :), but this was just a test.

After this tests then I went further to try to track down the problem and I 
saw acpi_ev_fixed_event_dispatch, that is the function that will call 
acpi_button_notify_fixed. First thing I noted: the comment about 
acpi_ev_fixed_event_dispatch says it will return INTERRUPT_HANDLED or 
INTERRUPT_NOT_HANDLED, but acpi_button_notify_fixed return AE_OK, is this 
right (comment is outdated) or am I missing something? Anyway I changed AE_OK 
to ACPI_INTERRUPT_HANDLED but this didn't change nothing. In the end I 
stopped there, doesn't seem to be anything wrong with the code at all, I also 
took a look at acpi_ev_fixed_event_detect and other code related to the table 
of fixed events (acpi_gbl_fixed_event_handlers), but didn't got more clues. 
Could be this a bios issue, or there is some hints to what I can try to look 
and prove that it's bios or code related?

PS.: with netconsole I don't get any message before power off after resume, I 
tried it to get more hints.

--
[]'s
Herton