Re: [2/2] 2.6.21-rc7: known regressions

["Antonino A. Daplas" <adaplas@gmail.com>]

On Mon, 2007-04-16 at 23:34 -0400, Dave Jones wrote:
> On Mon, Apr 16, 2007 at 10:26:43AM +0100, Richard Purdie wrote:
> 
>  > >  > >  > CONFIG_FB_BACKLIGHT=y
>  > >  > >  > CONFIG_ACPI_VIDEO=n
>  > >  > > 
>  > >  > > That also gets me a dead display. Backlight doesn't turn back on.
>  > >  > 
>  > >  > Anything under /sys/class/backlight?
>  > > 
>  > > Entries from ibm_acpi.  I rmmod'd that, leaving the dir empty,
>  > > and it still fails.
>  > 
>  > What happens if you never load ibm-acpi?
> 
> Same thing. No backlight on resume.
> I rm'd the .ko, so there's no chance it got loaded.
> 
>  > I'm a bit puzzled as CONFIG_FB_BACKLIGHT doesn't do anything with the
>  > intelfb driver. One thing it does do is set
>  > CONFIG_BACKLIGHT_CLASS_DEVICE. When you disabled FB_BACKLIGHT and got a
>  > working display on resume, was that set and was (or had) ibm-acpi been
>  > loaded?
>  > 
>  > A variety of other options such as ACPI_IBM also set
>  > CONFIG_BACKLIGHT_CLASS_DEVICE although without a backlight driver it
>  > will do nothing hence the suspicion is on ibm-acpi, perhaps interacting
>  > with the backlight class badly.
>  > 
>  > Does echoing numbers to /sys/class/backlight/ibm_acpi/brightness change
>  > the backlight brightness as expected?
> 
> /sys/class/backlight/ibm/brightness takes a value from 0 to 7.
> Starts off with a default of 0. I tried all values in there, and
> it made no visible difference.  But as the no-backlight thing happens
> without this even loaded, I think this is a separate problem.
> 
>  > If you can ssh into the machine
>  > after its resumed with the display problem, it would be interesting to
>  > know what the brightness was and if changing it helped too...
> 
> When the backlight doesn't come on, for some reason, nothing else
> runs.  Capslock works, so it's at least partially alive, but even
> doing..
> 
> echo mem > /sys/power/state ; echo foo >/bar ; sync
> 
> results in no /bar being created.
> Ethernet remains down when its in this state too.

Have you tried these boot options?

acpi_sleep=s3_mode; or
acpi_sleep=s3_bios,s3_mode

Tony