double power button events on presario 900 - apparently a timing issue?

as I previously mentioned I am seeing an annoying problem on my presario 900 - when power button (works as FF here) is pressed it generates two events every time. I was experimentin with debugging output and noticed an interesting thing - if I do
echo 0xffffffff > /proc/acpi/debug_level
to get verbose debug output the problem goes away - I only get one event every time button is pressed. Looks like the problem is caused by some kind timing issue which goes away when debugging slows it down. Does this sound like a reasonable guess? Would anyone suggest how this can be debugged further?

Quoted 10 lines · Fedor Karpelevitch

as I previously mentioned I am seeing an annoying problem on my presario 900 - when power button (works as FF here) is pressed it generates two events every time. I was experimentin with debugging output and noticed an interesting thing - if I do echo 0xffffffff > /proc/acpi/debug_level
to get verbose debug output the problem goes away - I only get one event every time button is pressed. Looks like the problem is caused by some kind timing issue which goes away when debugging slows it down. Does this sound like a reasonable guess? Would anyone suggest how this can be debugged further?

It means you need to debounce the event.

Quoted 12 lines · Nate Lawson

Quoted 10 lines · Fedor Karpelevitch

as I previously mentioned I am seeing an annoying problem on my presario 900 - when power button (works as FF here) is pressed it generates two events every time. I was experimentin with debugging output and noticed an interesting thing - if I do echo 0xffffffff > /proc/acpi/debug_level
to get verbose debug output the problem goes away - I only get one event every time button is pressed. Looks like the problem is caused by some kind timing issue which goes away when debugging slows it down. Does this sound like a reasonable guess? Would anyone suggest how this can be debugged further?

Quoted 1 line

It means you need to debounce the event.

do you mean debouncing on the receiving end? or would that be some way to avoid that in the kernel code?

Quoted 15 lines · Fedor Karpelevitch

Quoted 13 lines · Nate Lawson

Quoted 10 lines · Fedor Karpelevitch

as I previously mentioned I am seeing an annoying problem on my presario 900 - when power button (works as FF here) is pressed it generates two events every time. I was experimentin with debugging output and noticed an interesting thing - if I do echo 0xffffffff > /proc/acpi/debug_level
to get verbose debug output the problem goes away - I only get one event every time button is pressed. Looks like the problem is caused by some kind timing issue which goes away when debugging slows it down. Does this sound like a reasonable guess? Would anyone suggest how this can be debugged further?

It means you need to debounce the event.

Quoted 3 lines

do you mean debouncing on the receiving end? or would that be some way to avoid that in the kernel code?

by the way, I found that it is sufficient to do

echo 0x0800000f > /proc/acpi/debug_level and problem disappears. That bit is ACPI_DB_INTERRUPTS which is only referenced it two places...