Nouveau - Nov 2010 - [Bug 31920] New: Brightness control is erratic (/sys/class/backlight/nv_backlight/max_brightness is wrong)

https://bugs.freedesktop.org/show_bug.cgi?id=31920

           Summary: Brightness control is erratic
                    (/sys/class/backlight/nv_backlight/max_brightness is
                    wrong)
           Product: xorg
           Version: git
          Platform: Other
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/nouveau
        AssignedTo: nouveau at lists.freedesktop.org
        ReportedBy: rohandhruva at gmail.com
         QAContact: xorg-team at lists.x.org


I have a Sony Vaio CW2 laptop, with an Nvidia GeForce 310M card. I am using the
nouveau driver from git (via the xorg-edgers ubuntu repository). I have to say
it works really well - I even get desktop effects in KDE with Gallium. 

However, there is one problem with screen brightness. The max_brightness value
for the backlight interface (/sys/class/backlight/nv_backlight/max_brightness)
is set to 1025. When I use KDE power-devil (or any brightness control tool), it
reduces the brightness by tiny fractions, which still keeps the screen at full
brightness. The brightness actually varies only between 0 and 127 (128-1025 are
full brightness), and then too only if I change it in increments of 10 or 20. I
think ideally the max_brightness value should be 7 (or 10?) and it should vary
in steps of 1.

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--- Comment #1 from Rohan Dhruva <rohandhruva at gmail.com> 2010-11-25
10:08:13 PST ---
Created an attachment (id=40571)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=40571)
dmesg

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--- Comment #2 from Rohan Dhruva <rohandhruva at gmail.com> 2010-11-25
10:08:44 PST ---
Created an attachment (id=40572)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=40572)
xorg.log

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--- Comment #3 from Rohan Dhruva <rohandhruva at gmail.com> 2010-11-25
10:09:16 PST ---
Created an attachment (id=40573)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=40573)
lspci

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--- Comment #4 from Rohan Dhruva <rohandhruva at gmail.com> 2011-01-17
18:25:44 PST ---
For a while, I've been using the nvidiabl drive for brightness control. I
noticed that it correctly detects the max and min values for my laptop and
video card. I was wondering if the nouveau code could somehow benefit from the
work done by the nvidiabl author. The code is present here -
https://github.com/guillaumezin/nvidiabl

The corresponding thread is here --
http://www.nvnews.net/vbulletin/showthread.php?t=143025 and I think some
relevant updates/changes for my laptop model (VPCCW2) are here -
http://www.nvnews.net/vbulletin/showthread.php?t=143025&page=8

https://bugs.freedesktop.org/show_bug.cgi?id=31920

--- Comment #5 from Rohan Dhruva <rohandhruva at gmail.com> 2011-04-24
01:22:02 PDT ---
Is there a way to prevent nouveau from creating the
/sys/class/backlight/nv_backlight interface? If not, could it be added as a
kernel parameter? 

I find that brightness control works much better with the nvidiabl drivers, and
I'd prefer to use those with nouveau if possible.

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--- Comment #6 from Marcin Slusarz <marcin.slusarz at gmail.com>
2011-04-24 01:33:26 PDT ---
It would be better to integrate nvidiabl into nouveau.

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--- Comment #7 from Rohan Dhruva <rohandhruva at gmail.com> 2011-04-24
01:35:05 PDT ---
Agreed. Is there some way this could be kickstarted?

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--- Comment #8 from Rohan Dhruva <rohandhruva at gmail.com> 2011-04-24
01:41:18 PDT ---
I have filed a new issue on the nvidiabl tracker --
https://github.com/guillaumezin/nvidiabl/issues/8

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--- Comment #9 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-23
23:37:43 PDT ---
Hello.. Has there been any update on this? Thanks!

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--- Comment #10 from Ben Skeggs <skeggsb at gmail.com> 2011-09-23 23:50:21
PDT ---
Try the nouveau kernel git tree, there's been some updates there
semi-recently
to this area.

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--- Comment #11 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-25
22:19:47 PDT ---
I tried both the latest nouveau kernel git tree, and latest X.org packages from
git (via the xorg-edgers ubuntu repository). None of them fix this bug.

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--- Comment #12 from Ben Skeggs <skeggsb at gmail.com> 2011-09-26 04:57:33
PDT ---
What value does the various nv_backlight files have now?

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--- Comment #13 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-26
09:24:30 PDT ---
If anything, it has become less granular now. Here are some of the outputs:

rohan at ubuntu:/sys/class/backlight/nv_backlight$ cat max_brightness 
1025
rohan at ubuntu:/sys/class/backlight/nv_backlight$ cat actual_brightness 
615
rohan at ubuntu:/sys/class/backlight/nv_backlight$ cat brightness 
615
rohan at ubuntu:/sys/class/backlight/nv_backlight$ cat bl_power 
0
rohan at ubuntu:/sys/class/backlight/nv_backlight$ cat brightness 
103
rohan at ubuntu:/sys/class/backlight/nv_backlight$ 

IIRC, the max_brightness is still same as before (1025). However, the actual
"max" looks to be something around 615.

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--- Comment #14 from Emil Velikov <emil.l.velikov at gmail.com> 2011-09-26
11:57:26 PDT ---
Rohan

Can you please make sure that you are running nouveau kernel git tree [1] as
the official kernel does _not_ yet have those changes

If you are interested what those changes are, here is the list [2]


Thanks

[1] http://cgit.freedesktop.org/nouveau/linux-2.6/
[2]
http://cgit.freedesktop.org/nouveau/linux-2.6/log/drivers/gpu/drm/nouveau/nouveau_backlight.c

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--- Comment #15 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-26
11:59:55 PDT ---
Emil: Thank you for the links! I'm indeed running the latest DRM code. I
followed the instructions here --
http://nouveau.freedesktop.org/wiki/InstallDRM. I cloned the repo without
history, and did an out-of-tree build.

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--- Comment #16 from Emil Velikov <emil.l.velikov at gmail.com> 2011-09-26
12:21:16 PDT ---
Rohan

If you are using the latest kernel code, nouveau will report
"max_brightness==100"

See commit drm/nv50/backlight: express brightness level in percent - bc0df418

Cheers
Emil

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--- Comment #17 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-26
12:29:25 PDT ---
I just did a git pull, make clean, and recompiled the modules. My modules.dep
file also shows that the extra/ directory is being used for nouveau modules. Is
there anything else I must be doing? I'm quite sure that the stock ubuntu
modules are being overriden.

I'm also attaching my dmesg and xorg.log to be sure :)

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--- Comment #18 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-26
12:30:13 PDT ---
Created an attachment (id=51641)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=51641)
Latest dmesg

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Rohan Dhruva <rohandhruva at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #40571|0                           |1
        is obsolete|                            |
  Attachment #40572|0                           |1
        is obsolete|                            |

--- Comment #19 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-26
12:30:46 PDT ---
Created an attachment (id=51642)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=51642)
Latest xorg.log

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--- Comment #20 from Ben Skeggs <skeggsb at gmail.com> 2011-09-26 15:34:52
PDT ---
(In reply to comment #17)
> I just did a git pull, make clean, and recompiled the modules. My
modules.dep
> file also shows that the extra/ directory is being used for nouveau
modules. Is
> there anything else I must be doing? I'm quite sure that the stock
ubuntu
> modules are being overriden.
> 
> I'm also attaching my dmesg and xorg.log to be sure :)
I'm afraid somehow you're still getting the old driver loaded.  The code
in
nouveau git *cannot* report max_brightness of 1025 anymore, as evidenced by
this section of the patches linked above:

-       props.max_brightness = 1025;
+       props.max_brightness = 100;

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--- Comment #21 from Rohan Dhruva <rohandhruva at gmail.com> 2011-09-26
15:47:25 PDT ---
Is there any way I can debug this issue? Maybe modify some other file I can
modify? Delete the older modules? Thank you for your patience. 

Btw, when will this code merge into mainstream? I was wondering if we'll see
it
in next release of major distros.

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--- Comment #22 from Ben Skeggs <skeggsb at gmail.com> 2011-09-26 16:01:12
PDT ---
(In reply to comment #21)
> Is there any way I can debug this issue? Maybe modify some other file I can
> modify? Delete the older modules? Thank you for your patience. 
I suggest perhaps deleting any directory in /lib/modules that contains
nouveau.ko/drm.ko and friends, then reinstalling them from the nouveau git tree
you built.

> 
> Btw, when will this code merge into mainstream? I was wondering if
we'll see it
> in next release of major distros.
The patches are queued for kernel 3.2.

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--- Comment #23 from Lucas Stach <dev at lynxeye.de> 2011-09-27 01:09:13
PDT ---
Don't know if Ubuntu uses this, but Fedora stuffs the nouveau driver into
the
initrd. If Ubuntu does a similar thing you have to rebuild your initrd after
installing the new modules to get your newly built nouveau loaded.

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Rohan Dhruva <rohandhruva at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #25 from Rohan Dhruva <rohandhruva at gmail.com> 2012-03-31
23:00:06 UTC ---
This has been working for me since kernel 3.1, in Fedora 16. I also tried
kernel 3.2 in Ubuntu 12.04, and it has been working fine out of the box.

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--- Comment #24 from Alex Mayorga Adame <alex_mayorga at yahoo.com>
2012-03-31 22:55:16 PDT ---
Did this make it into kernel 3.2? What can be done for the brightness controls
to work properly?

I reported https://bugs.launchpad.net/nouveau/+bug/551668 a while ago on
Ubuntu's bug tracker I believe is this bug or a related one and it is still
causing problems on the following configuration:

alex-mayorga at VPCCW1FFXL:~$ uname -a
Linux VPCCW1FFXL 3.2.0-21-generic #34-Ubuntu SMP Fri Mar 30 04:25:35 UTC 2012
x86_64 x86_64 x86_64 GNU/Linux
alex-mayorga at VPCCW1FFXL:~$ lspci -nn | grep VGA
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GT216 [GeForce GT
230M] [10de:0a2a] (rev a2)
alex-mayorga at VPCCW1FFXL:~$ apt-cache show xserver-xorg-video-nouveau
Package: xserver-xorg-video-nouveau
Priority: optional
Section: x11
Installed-Size: 344
Maintainer: Ubuntu Developers <ubuntu-devel-discuss at lists.ubuntu.com>
Original-Maintainer: Debian X Strike Force <debian-x at lists.debian.org>
Architecture: amd64
Version: 1:0.0.16+git20111201+b5534a1-1build2
Provides: xorg-driver-video
Depends: libc6 (>= 2.4), libdrm-nouveau1a (>= 2.4.23), libudev0 (>=
147),
xorg-video-abi-11, xserver-xorg-core (>= 2:1.10.99.901)
Recommends: libgl1-mesa-dri (>= 7.11.1)
Filename:
pool/main/x/xserver-xorg-video-nouveau/xserver-xorg-video-nouveau_0.0.16+git20111201+b5534a1-1build2_amd64.deb
Size: 109400
MD5sum: 5ab8e5861a11a57d783fa9862d88900f
SHA1: 7abb48438df08eed97dd4676bc111bdbaf714376
SHA256: 886d7e2f968819373d81a932388ede20995d9bd1d3d8f2091100f988a314a780
Description-en: X.Org X server -- Nouveau display driver
 This driver for the X.Org X server (see xserver-xorg for a further
description)
 provides support for NVIDIA Riva, TNT, GeForce, and Quadro cards.
 .
 This package provides 2D support including EXA acceleration, Xv and
 RandR.  3D functionality is provided by the libgl1-mesa-dri package.
 .
 This package is built from the FreeDesktop.org xf86-video-nouveau driver.
Homepage: http://nouveau.freedesktop.org/wiki/
Description-md5: b084a16945b86c1eda89ad33dbb4530d
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Origin: Ubuntu
Supported: 5y
Task: ubuntu-desktop, ubuntu-usb, kubuntu-desktop, kubuntu-active-desktop,
kubuntu-active, edubuntu-desktop, edubuntu-usb, xubuntu-desktop,
mythbuntu-frontend, mythbuntu-desktop, mythbuntu-backend-slave,
mythbuntu-backend-master, lubuntu-core, ubuntustudio-desktop

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