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Re: Backlight mystery - anyone shed light? some progress

On 24 Apr 2011, Camaleón wrote:
> On Sun, 24 Apr 2011 10:49:26 +0100, Anthony Campbell wrote:
> > On 23 Apr 2011, Camaleón wrote:
> >> Also, check for a BIOS update, most of these "ACPI things" are usually
> >> fixed after updating to the latest BIOS.
> >> 
> >> 
> > Thanks, Camaleon. I found a lot of people using the same laptop with
> > Windows who have the same problem. In some cases a bios upgrade fixed
> > it, in others not. I tried to do this but it requires using an .exe
> > file, and though I could do this with both wine and dosemu I couldn't
> > obtain a suitable iso file to do the upgrade. (Also, I was a little
> > afraid of ending up with an unbootable machine, which a few people
> > report as happening.)
> Don't be afraid of a BIOS update. Laptops need this piece of code to be 
> updated more often than desktops machines due to buggy firmware and 
> notebook's embedded nature.
> What happens here is that manufacturers do not always provide a utility 
> to extract the update file in order you can put it into a USB/CD-ROM to 
> run the update and sadly the complete procedure needs to be done in a 
> windows environment.
> (That's one of the reasons why it is a good idea to do not remove the 
> windows partition although you don't use it on your day work :-/)

Yes, I was keeping it for that reason, but unfortunately it has ceased
to work for some reason.

> > BUT I have found that by unloading and reloading the video module
> > (and/or the radeon module) I can sometimes obtain the requisite
> > backlight file in /sys/devices/virtual .., after which the screen either
> > becomes bright automatically or I can do it manually. So it seems to be
> > something to do with the order in which the modules are loaded, though I
> > can't figure out what. The effect is unpredictable - sometimes it works,
> > sometimes not.
> If you can wait with that bypass, msot sure is that any kernel update 
> will solve the problem as you seemed to experience with 2.6.37 and 2.6.38 
> branches.

There was an upgrade of 2.6.38 in unstable today and also an upgrade of
udev. Unfortunately I now can't even get 2.6.37 to work reliably, though
it did after a bit of fiddling. It's just hit and miss. I've come to the
conclusion I hate all laptops!

Anthony Campbell - ac@acampbell.org.uk 
Microsoft-free zone - Using Debian GNU/Linux 
http://www.acampbell.org.uk - sample my ebooks at

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