generic nVidia driver maintaining brightness controls

[will_ssi]

Hello everyone, I'm a relatively new thinkpad owner. I found a used T61 on ebay several months ago, and have been very happy with it ever since. Just before I put the money down for it, I found this community and it has been a great resource for me.

My T61 came with Vista Business, so I immediately reformatted and put XP on it. I used all the most up-to-date drivers on the Lenovo (really IBM) support site, and was disappointed to see that the most recent Lenovo approved nvidia driver was from Jan 14th, 2009. I shrugged and went with it until yesterday, when I was getting sluggish video in this indie platformer called Braid. I did some digging, and found that laptopvideo2go.com hosts all the nvidia drivers with modified infs so they can be installed on any laptop system. Great I thought, and I went ahead and put 190.89 on the laptop. To my horror though, the screen brightness reset to its lowest setting, and despite the OSD showing that I was increasing the brightness it would not go above the 'minimum'. Driver tweaks, power manager tweaks, nothing would fix this. Going back to the Lenovo approved driver fixed my problem, but I didn't want to be stuck with an out of date video driver for the life of my T61.

Long story short, after some googling and reading a bunch of frustrated linux / win7 users talking about this problem, I got it fixed. I did a search in this forum, and the FAQs one and didn't see this documented so I thought I would share it.

After you have downloaded the video driver you want to install, and the modified inf, you need to open up the inf and find the section marked "[nv_commonBase_addreg]". Every [nv_common*_addreg] and [nv_misc*_addreg] (* == wildcard) heading should have the line "HKR,, EnableBrightnessControl, %REG_DWORD%, 0x00000001" added to it. Don't put this in any section that contains delreg or controlpanel. If you install the driver now, brightness control will work just as it does with the January 14th driver.

This is somewhat a shot-gun approach to fixing the problem, because I believe the entry only needs to go under 2 headings, but I don't know which 2. Looking at the Lenovo approved driver, it appears that nvidia changed how they wrote the infs for their drivers so the sections that contain the brightness control in the approved driver don't exist in the new nvidia drivers. But I believe it would go under [nv_commonBase_addreg__01] and [nv_commonBase_addreg__02] (based on common entries between the two driver versions). I haven't checked this though, because I haven't had any problems with the way I did it originally.

If that helps anyone, I'll be happy. If this is a re-post / known info, sorry for the spam.

[irichie]

Thanks for sharing! This worked with the latest laptopvideo2go.com drivers! Been looking for a solution for some time now.
I have a T61 with the NVS140M and have had issues with the latest Lenovo drivers last updated in Feb 09.

Only had to add it in one location to work under [nv_commonBase_addreg].

I think this really deserves a sticky!