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Old 06-07-09, 09:34 AM   #1
schmirrwurst
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Unhappy No backlight information in /sys/class nor laptop_panel

Backlight problem is remaining on sony vaio with geforce8...
Some changes have been made to hal to solve the problem, but for some hardware the problems remains because lshal doesn't show any laptop_panel and the backlight directory in /sys/class remains empty

Any Idea of what is going wrong ? Should it be fixed in the kernel, or in the driver... ??
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Old 06-07-09, 09:39 AM   #2
schmirrwurst
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Default log and hw detail on launchpad bug :

https://bugs.launchpad.net/ubuntu/+s...ux/+bug/377353
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Old 07-02-09, 03:57 PM   #3
schmirrwurst
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Default Re: No backlight information in /sys/class nor laptop_panel

I've reported this problem to the kernel team, and it seems that it is definitly a platform driver problem...
Would it be possible to modify the driver so that it will be giving backlight information at /sys/class/backlight/ ??

I'm trying to find a solution for this for almost 20 months..
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Old 07-02-09, 03:59 PM   #4
schmirrwurst
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Default Re: No backlight information in /sys/class nor laptop_panel

I'm experiencing those problem with drivers from 178 to 185.18.14
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Old 07-02-09, 06:07 PM   #5
_john_i_
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Default Re: No backlight information in /sys/class nor laptop_panel

I have an MSI 171-F laptop with nvidia 8200M G, and I have no control of the backlight either, and I am missing entries under /sys and /proc for backlight control as well.

I really wish there was a way to get it to work.
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Old 07-03-09, 02:05 AM   #6
schmirrwurst
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Default Re: No backlight information in /sys/class nor laptop_panel

I john, good to know that I'm not alone with that problem, I though it is only on sony laptop...
Could you try to report also on kernel bugzilla... ?
Perhaps you could report and attach the same logs as I was asked to...
http://bugzilla.kernel.org/show_bug.cgi?id=13477
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Old 07-03-09, 02:14 AM   #7
schmirrwurst
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Default Re: No backlight information in /sys/class nor laptop_panel

You can also report here if using ubuntu :
https://bugs.launchpad.net/ubuntu/+s...80/+bug/377353

I still hope that someone from the nvidia team is going to be interested by this issue...
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Old 07-06-09, 12:15 PM   #8
schmirrwurst
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Default Re: No backlight information in /sys/class nor laptop_panel

acpi is managed from devicekit-power and udev in ubuntu (hal and acpi scripts are depreciated)
udev and devicekit-power don't wan't to write driver specific code, because that's why hal project is stopping...

So a nvidia driver giving an interface to control backlight in /proc /sys is REALLY needed !
A lot of people are not able to use there laptop with nvidia properly !!
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Old 07-06-09, 05:35 PM   #9
_john_i_
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Default Re: No backlight information in /sys/class nor laptop_panel

For what I understand from researching this is different laptop vendors can have slightly different ways controlling the backlight, and since there is no one standard nvidia can't maintain different settings for every vendor that changes it. That is why they don't provide windows drivers for mobile gpu's and require the vendors to supply them.

I would be happy if I just knew the register to change so I could modify the smartdimmer app that comes with nvclock.

Interestingly, before linux loads (at the grub prompt), I can use the fn key to adjust the backlight - once booted, though there is no way to change it in linux. It does seem to stay at what I change it to before boot.
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Old 07-07-09, 11:29 AM   #10
schmirrwurst
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Default Re: No backlight information in /sys/class nor laptop_panel

Wich version from nvclock are you using ?
before beta4, it wasn't working for me, but now with b4 it do...

if b4 is not working for you, perhaps you could search launchpad, I had subrscribe a bug because of backlight, and someone calle mike, was able to find out the register from the windows driver and update nvclock...

Are nvclock and smartdimmer not made from nvidia developpers ?
Because if they work, and had been update to work with several laptops, then there is no reason not to change the driver itself to provide backlight support ...

The problem is that the laptop manufacturer does not support linux, what to do then ?
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Old 07-07-09, 05:48 PM   #11
_john_i_
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Default Re: No backlight information in /sys/class nor laptop_panel

No, even beta4 does not work for my laptop, which was brand new as of December, so maybe no one has figured out what to update.

Nvidia doesn't maintain nvclock and its smartdimmer app, it is an independent opensource program.

I made some modifications to smartdimmer to dump out more address ranges then I would reboot and adjust brightness at bios screen, and dump again to try to find the change, but no luck yet

Can you give me a link to the discussion board where mike found the register from the windows driver? I am unable to find it with a search. If there is a way to read it from the windows driver package, I am pretty sure I can modify smartdimmer to work for me.
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Old 07-09-09, 11:40 AM   #12
schmirrwurst
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Angry Re: No backlight information in /sys/class nor laptop_panel

It's a shame that even with brand new computer the problem remains... and I think a it is to nvidia to provide a solution, perhaps someone from nvidia will post an answer a day...

I bought my sony second hand, so I've no access to vaio club, but you could register yours, and then ask to the forum for minimum linux support... I think I've already seen a thread there, if many people are asking for it, something may maybe happen !!

To find out the register, maybe you could ask on the nvclock forum, so that thunderbird (the maintainer) could add a fix for your laptop to the next release...
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