[SOLVED] Backlight fails frequently on boot with custom kernel
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Backlight fails frequently on boot with custom kernel
Hi, first post here.
I have been having issues with my netbook's backlight on a 3.0 kernel I have compiled. Every few boots, the screen will turn fullbright, as the kernel prints out:
ACPI Error: Current brightness invalid (20110413/video-377)
Any attempts to change the brightness with the fn keys afterwards causes this to be printed out:
ACPI: Failed to switch the brightness
Rarely (I've only gotten this once) I can change the brightness afterwards, even though it still prints out the errors. When I look in /sys/class/backlight/ when the errors get thrown, it is completely empty, otherwise it has a folder named acpi_video0.
This happens both with a .config based on the (working) Arch Linux kernel I am running now, and with a "make defconfig" that I tweaked to include the drivers that I want. I'm a bit confused as to where to start looking for a solution since the majority of the time it does work properly. It's just the times when the screen gets forced to an eye-searing brightness that I have problems.
If anyone is able to help, I would be most appreciative. Thanks in advance.
I'd prefer to avoid hacks like that since the backlight works perfectly on Arch Linux supplied kernels.
Originally Posted by EDDY1
Ialso noticed you have settings for dual-head not sure if it's relevant
You mean "ACPI: Video Device [OVGA] (multi-head: yes rom: no post: no)"? It's the same on the working kernel.
Oh, and I believe that I forgot to mention that the previous kernel I had compiled myself (2.6.35) had very similar issues. I can't say exactly since it was a while ago and I didn't pay too much attention to it.
Are you just compiling for the fun of it or for a specific reason?
Also the suggested info was not a hack if you read it it gives you control of the adjustments up & down, I elieve that you looked at the first option 50% not at the full configuration file, have you checked your settings.
I am doing this just for "fun". I also wanted to set my CPU type to Intel Atom and take advantage of any optimization that did.
The backlight fix you linked to was, in fact, a hack. It was a workaround fix for something that sometimes works on this kernel, and that always works on Arch Linux supplied kernels. It addresses the symptoms, not the cause. Sorry, but that is no solution for me.
"acpi_backlight=vendor" does not help, I had tried it prior to posting here. If I recall correctly, it just made the backlight go fullbright 100% of boots. Furthermore, the launchpad link is old, and it does not accurately portray my problem.
Arch Linux's newly released Linux 3.0 does not have this issue.
I am now going to try compiling with this currently working config to see if I still run into problems. If I do, then I will look and see what patches Arch Linux might have applied and see if any of them fix it.
I have just compiled Linux 3.0.1 from source using an unmodified Arch Linux config. It does not appear to have the backlight issue.
At this point, I am confused as to what I did that broke it. It's not like there's an option in the setup named "Make backlight work on only some boots". Common sense says that the backlight would either work 100% or 0% of the time, depending on whether the driver was installed, right?
Nice to know that you have solved your issue, I recently upgraded from wheezy 2.6.38 to 3.0 on my laptop & am working thru my issues, laptop mode wasn't working also Gtk pixbuff, partially fixed, had to edit /usr/sbin/laptop_mode for unhandled kernel version errors. I have a few more issues but they'll soon be resolved. My virtual machine works fine though.