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SubjectRe: apm suspend broken ?
Hello Everyone,

Some news about the APM problem on Dell Latitude C600:

On Thu, 1 Nov 2001, Stephen Rothwell wrote:
> Can you try the following patch, please? This is the relevant part of a
> patch that was applied to Alan Cox's kernels.

I tested this patch against 2.4.10-pre12 (first version showing problem)
and 2.4.13.
I tested also plain 2.4.13-ac5 since you (Stephen) said that this patch
was taken from the last Alan kernel.

Both kernels show the same behaviour, so please read on since 2.4.13-ac5
is impacted by this bug.


I tested the patch against 2.4.10-pre12.
(I had to suppress a line in arch/i386/kernel/dmi_scan.c to make it compile
since it defined pm_kbd_request_override differently than the definition in
keyboard.h) The patch seemed to correct the apm behaviour nicely (I use
'seem' since I tried it only once in a hurry to test against 2.4.13).

So I tested the same patch against 2.4.13. It went through without any
reject, compilation was fine also ... I tested also 2.4.13-ac5 and both
show the same ill behaviour:

Fn+Suspend (or launching "apm -s") does not ALWAYS suspend the laptop.
Sometimes, it blanks the screen but leaves the lcd light on, the cpu fan is
on also. Pressing Fn+D to turn off the lcd light completes the job and the
laptop finaly suspends completely.
Typing "apm -s" shows the same behaviour, it did suspend the laptop ONCE out
of 12 tests, all other 11 tests required to press Fn+D after to suspend.

By the way, If I hit ANY key between Fn+Suspend and Fn+D, the keyboard
is misbehaving after resume: CapsLock is inverted, Ctrl, Shift and Alt
are dead.

Under some rare conditions, apm -s works, but in general, asking the bios
to turn off the lcd light (Fn+D) helps a lot.
I guess the keyboard problem is not a real one since if "apm -s" did its job
completely I would no chance to press any key before the lcd light goes off.

Statistically, 2.4.13-ac5 seems to show better luck in suspending (it works
correctly more often than 2.4.13+patch from Stephen).

Pascal

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