Backlight gets reseted with VDPAU

damdim · 12-02-10, 12:15 PM

I have an issue with the brightness of my laptop (VAIO VPCCW1S1E with GT230M) and I want to track down the cause of it. I have installed nvidiabl and it works great. The problem is that If I don't use composite of the window manager, then when I try to play a video with VDPAU output then the backlight is reseted to its' maximum value. If I use a composition window manager with opengl rendering, then the backlight is reseted even when I run a 3D app f.e. glxgears. If I use Xrender instead of opengl, then the backlight is not reseted neither with VDPAU nor with 3D apps. This happens in GNOME and KDE and it doesn't happen in another laptop with Intel integrated graphics. Do you have an idea of what might causing this behavior?

zchronos · 12-02-10, 11:20 PM

Me too!

Card: GeForce GT220 (XFX - 1GB DDR2)
Nvidia Driver: NVIDIA-Linux-x86_64-260.19.21.run
S.O: openSUSE 11.3 (x86_64)
kernel: 2.6.34.7-0.5-desktop
D.E: KDE 4.5.3

VDPAU es awesome fast, but... la 260.19.21 have bugs with the colors (bright, constrast, ganma are reset).

**Stephen Warren** · 12-03-10, 11:41 AM

Does this still happen without nvidiabl? I can't really find any information on nvidiabl, but I'd suggest contacting the maintainers of that application first, since you're explicitly controlling your backlight with it.

damdim · 12-03-10, 12:02 PM

It's a module I found in this forum.
http://www.nvnews.net/vbulletin/showthread.php?t=143025
Without it I cannot control backlight even with:

Code:

Option "RegistryDwords" "EnableBrightnessControl=1"

alessandro_ufms · 12-06-10, 08:42 AM

It's happens to me on fullscreen flash videos.

xificurk · 12-27-10, 06:02 PM

I have Dell Vostro 3700 (GeForce GT 330M), kernel 2.6.36 and nvidia-drivers 260.19.29 and have the same problem. I have found out that when the compositing in KDE4 is switched on/off, "something" (probably nvidia-driver) resets the brightness level of the display to the last value set by Fn keys, ignoring the current level.
I assume the switch of compositing is a trigger - I can see this happen also when e.g. going to fullscreen video playback or switching to VT (but only when compositing is enabled).

guillaumezin · 01-09-11, 09:08 AM

Quote:

Originally Posted by Stephen Warren

Does this still happen without nvidiabl? I can't really find any information on nvidiabl, but I'd suggest contacting the maintainers of that application first, since you're explicitly controlling your backlight with it.

Hello,

I'm the maintainer of the nvidiabl module. Do you have any kind of information on the meaning of bit 30 and 31 of the brightness register (@c084)? As you can see here: http://www.nvnews.net/vbulletin/show...=1#post2374990 the register is restored by another module (I don't know wich one) with bit 30 set.

Thank you.

Best regards

Guillaume

**Stephen Warren** · 01-10-11, 10:47 AM

guillaumezin,

I'm sorry, but NVIDIA doesn't publish the programming information for our GPUs, so I can't provide that information.

Can you explain in more detail what nvidiabl does, and why it's needed, and how it interacts with VDPAU? Thanks.

guillaumezin · 01-10-11, 04:10 PM

Quote:

Originally Posted by Stephen Warren

guillaumezin,

I'm sorry, but NVIDIA doesn't publish the programming information for our GPUs, so I can't provide that information.

Can you explain in more detail what nvidiabl does, and why it's needed, and how it interacts with VDPAU? Thanks.

Complete sources are here: https://github.com/guillaumezin/nvidiabl

nvidiabl doesn't interact at all with nvidia driver or VDPAU, it only plays with the brighness register (relative address 0xc084) - I got this register address from the nvclock project (http://www.linuxhardware.org/nvclock) and similar brightness drivers (http://wingolog.org/pub/nvbacklight-0.1.tar.bz2 and https://launchpad.net/~mactel-support-community)

**Stephen Warren** · 01-10-11, 05:42 PM

I guess this problem isn't surprising then; the nvidia kernel driver owns all GPU registers and has no provisions to share them. Hence, any changes made by nvidiabl can and will get over-written. I'd imagine this is happening with VDPAU in particular, because it programs various display registers to set up the overlay.

Why is nvidiabl needed; are there bugs in the nvidia driver that should be addressed instead?

damdim · 01-11-11, 12:16 AM

Quote:

Originally Posted by Stephen Warren

Why is nvidiabl needed; are there bugs in the nvidia driver that should be addressed instead?

Because without nvidiabl we cannot control the backlight of various laptops based on nvidia GPUs.

guillaumezin · 01-11-11, 11:22 AM

Quote:

Originally Posted by damdim

Because without nvidiabl we cannot control the backlight of various laptops based on nvidia GPUs.

+1

Playing with this register is today the only solution to control the backlight on every laptops equipped with modern nVidia GPU. And the nvidia driver doesn't handle at all the backlight, this is not a bug, this is more a missing feature, quite complicated to implement because values to be used in this register are dependant on laptop brand and model.

Guillaume

12-02-10, 12:15 PM	#1
damdim Registered User Join Date: Jan 2010 Posts: 21	Backlight gets reseted with VDPAU I have an issue with the brightness of my laptop (VAIO VPCCW1S1E with GT230M) and I want to track down the cause of it. I have installed nvidiabl and it works great. The problem is that If I don't use composite of the window manager, then when I try to play a video with VDPAU output then the backlight is reseted to its' maximum value. If I use a composition window manager with opengl rendering, then the backlight is reseted even when I run a 3D app f.e. glxgears. If I use Xrender instead of opengl, then the backlight is not reseted neither with VDPAU nor with 3D apps. This happens in GNOME and KDE and it doesn't happen in another laptop with Intel integrated graphics. Do you have an idea of what might causing this behavior?

12-03-10, 11:41 AM	#3
Stephen Warren Moderator Join Date: Aug 2005 Posts: 1,327	Re: Backlight gets reseted with VDPAU Does this still happen without nvidiabl? I can't really find any information on nvidiabl, but I'd suggest contacting the maintainers of that application first, since you're explicitly controlling your backlight with it.

12-03-10, 12:02 PM	#4
damdim Registered User Join Date: Jan 2010 Posts: 21	Re: Backlight gets reseted with VDPAU It's a module I found in this forum. http://www.nvnews.net/vbulletin/showthread.php?t=143025 Without it I cannot control backlight even with: Code: Option "RegistryDwords" "EnableBrightnessControl=1"

12-06-10, 08:42 AM	#5
alessandro_ufms Registered User Join Date: Jan 2009 Posts: 23	Re: Backlight gets reseted with VDPAU It's happens to me on fullscreen flash videos.

12-27-10, 06:02 PM	#6
xificurk Registered User Join Date: Dec 2010 Posts: 4	Re: Backlight gets reseted with VDPAU I have Dell Vostro 3700 (GeForce GT 330M), kernel 2.6.36 and nvidia-drivers 260.19.29 and have the same problem. I have found out that when the compositing in KDE4 is switched on/off, "something" (probably nvidia-driver) resets the brightness level of the display to the last value set by Fn keys, ignoring the current level. I assume the switch of compositing is a trigger - I can see this happen also when e.g. going to fullscreen video playback or switching to VT (but only when compositing is enabled).

01-10-11, 10:47 AM	#8
Stephen Warren Moderator Join Date: Aug 2005 Posts: 1,327	Re: Backlight gets reseted with VDPAU guillaumezin, I'm sorry, but NVIDIA doesn't publish the programming information for our GPUs, so I can't provide that information. Can you explain in more detail what nvidiabl does, and why it's needed, and how it interacts with VDPAU? Thanks.

01-10-11, 05:42 PM	#10
Stephen Warren Moderator Join Date: Aug 2005 Posts: 1,327	Re: Backlight gets reseted with VDPAU I guess this problem isn't surprising then; the nvidia kernel driver owns all GPU registers and has no provisions to share them. Hence, any changes made by nvidiabl can and will get over-written. I'd imagine this is happening with VDPAU in particular, because it programs various display registers to set up the overlay. Why is nvidiabl needed; are there bugs in the nvidia driver that should be addressed instead?