apm screen blanking.

C. Scott Ananian (cananian@lcs.mit.edu)
Wed, 25 Feb 1998 17:27:16 -0500 (EST)

On Wed, 25 Feb 1998, Garst R. Reese wrote:

> In X the screen blanks after 8 min. This was the blank time I had my
> bios set to when I installed X, but I have since changed it to 2 min. On
> a non X VC it blanks and turns off the backlight in 2 min.
> XFree86 v3.2 linux-2.1.88 MidWestMicro Elite SoundBook DX2/66 mono.

I'm currently concentrating on finding the bug that causes notebooks to
hang on 'suspend to disk' in linux (but not NT/win95! [argh]), but I've
gotten several messages of this type. I've heard comments on the list
that 'X screen blanking is broken' -- can anyone explain this further?
Most apm bug reports say that non-X VCs are fine, so at this moment I'm
blaming this on XFree86.

Would performing a VESA power-off help, in addition to possibly faulty APM
screen blanking? [the current linux kernel does not do the VESA power-off
if the APM screen-blanking reports success].

[I should note that this problem is *not* related to the APM 1.2 updates,
although I have suggested various patchlets to people in an attempt to
narrow down the problem. Nothing that I've come up with has made the
problem go away, however, so no screen-blanking-related changes have been
made to the standard linux apm driver. I just thought I should mention
that after receiving some messages with 'buggy apm_bios updates' in the
subject. This subject is factually incorrect. It is true that none of
the patch*lets* have fixed the problem. I made no guarantee they would.
They were for debugging--I had to figure out just how badly the APM bios
was broken. The apm updates being integrated into the kernel (partial
integration in 2.1.88, hopefully the final patch will make it to 2.1.89)
have *nothing to do* with these screen blanking problems. All bug reports
regarding screen blanking that I have received to date seem to be either
1) buggy APM implementations from some vendors (the 'invalid device'
responses from the BIOS), or 2) Xfree86 problems (?) -- things that work
fine when X is not running. The reports on the patchlets I have suggested
seem to confirm this conclusion. I am not convinced there are any
screen-blanking bugs in the linux *kernel*. If I find any, I'll fix
them, of course.]

<useful request>
I'd appreciate if a number of notebook users with suspend-to-disk problems
could drop be a quick line. I'd like to a) compile a list of
known-problematic laptops to put in the documentation, and b) have a list
of people to distribute debugging code or alpha patches to.
</useful request>
@ @
C. Scott Ananian: cananian@lcs.mit.edu / Declare the Truth boldly and
Laboratory for Computer Science/Crypto / without hindrance.
Massachusetts Institute of Technology /META-PARRESIAS AKOLUTOS:Acts 28:31
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