apm standby on thinkpad

apm standby on thinkpad

[Alexander Mirgorodskiy]

Folks,

I ran into a problem with APM on a Thinkpad T41: the system cannot
properly resume after a standby. The backlight turns on, but the
screen remains blank. This happens on keypress (fn-f3) and
idle-time-induced standbys. However, resume after "apm -S" works just
fine.

I inserted some trace statements into the apm kernel driver and found
that it does not seem to receive standby and resume notifications from
BIOS if standby is initiated through fn-f3. At the same time, it does
receive the notification on a resume from "apm -S".

Any idea why that happens?

Thanks,
Alex

--

P.S: I see this on a RedHat 9 system with the 2.4.20 kernel. For a
bunch of reasons, I cannot upgrade to anything else in the short
term. (I did try 2.4.26, but it behaved even worse -- didn't wake up
at all, even if standby was entered with "apm -S")

Re: apm standby on thinkpad

[john stultz]

On Wed, 2004-05-19 at 06:48, Alexander Mirgorodskiy wrote:
> Folks,
> 
> I ran into a problem with APM on a Thinkpad T41: the system cannot
> properly resume after a standby. The backlight turns on, but the
> screen remains blank. This happens on keypress (fn-f3) and
> idle-time-induced standbys. However, resume after "apm -S" works just
> fine.
> 
> I inserted some trace statements into the apm kernel driver and found
> that it does not seem to receive standby and resume notifications from
> BIOS if standby is initiated through fn-f3. At the same time, it does
> receive the notification on a resume from "apm -S".
> 
> P.S: I see this on a RedHat 9 system with the 2.4.20 kernel. For a
> bunch of reasons, I cannot upgrade to anything else in the short
> term. (I did try 2.4.26, but it behaved even worse -- didn't wake up
> at all, even if standby was entered with "apm -S")

Just for a datapoint, I cannot reproduce the issue using 2.6.6 on a T40
installed with Fedora Core 1.
-john

Re: apm standby on thinkpad

[Alexander Mirgorodskiy]

> Just for a datapoint, I cannot reproduce the issue using 2.6.6 on a T40
> installed with Fedora Core 1.

Thank you for checking, it made me try 2.6.6 and I still see the same 
problem.

The good news is, the problem does not happen on a virtual console, only 
in X. In fact, I narrowed it down to radeon_drv.o in X11 from RedHat 9. 
After replacing just that file with the one from a recent Debian 
machine, the problem went away.

Both modules report the same version (4.0.1), but were compiled for 
slightly different X distributions (4.3.0 in RedHat vs 4.3.0.1 in Debian).

Alex

Re: apm standby on thinkpad

[Alexander Mirgorodskiy]

Alexander Mirgorodskiy wrote:
> [...]
> 
> (I did try 2.4.26, but it behaved even worse -- didn't wake up
> at all, even if standby was entered with "apm -S")

I have finally narrowed that second problem down to the 
CONFIG_X86_UP_APIC flag (Local APIC support on uniprocessors). That is, 
when the flag is set to "y", ThinkPad T41 cannot wake up after APM 
standby ("apm -S" or Fn-F3). It isn't specific to 2.4.26, happens on 
other 2.4 kernels I tried, as well as on 2.6.6.

Does anybody else see this problem on similar hardware?

Thanks,
Alex