Bug 677694 - /sys/class/backlight/nv_backlight/max_brightness is set to lower value after suspend on battery power giving dim display
Summary: /sys/class/backlight/nv_backlight/max_brightness is set to lower value after ...
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: rawhide
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-02-15 15:53 UTC by Greg Crichton
Modified: 2011-02-21 12:02 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2011-02-21 12:02:38 UTC
Type: ---


Attachments (Terms of Use)
lspci -vv -nn -d 10de:0a29 (2.73 KB, application/octet-stream)
2011-02-15 15:53 UTC, Greg Crichton
no flags Details
/var/log/messages excerpt after issue (408.31 KB, application/octet-stream)
2011-02-15 16:02 UTC, Greg Crichton
no flags Details
Xorg log (29.86 KB, application/octet-stream)
2011-02-15 16:03 UTC, Greg Crichton
no flags Details

Description Greg Crichton 2011-02-15 15:53:22 UTC
Created attachment 478899 [details]
lspci -vv -nn -d 10de:0a29

Description of problem:
On boot with updated Rawhide on Samsung R590 laptop (Nvidea GM330) /sys/class/backlight/nv_backlight/max_brightness is set to 1073864551
The brightness is fine for viewing and controllable via keys. If power cable is connected suspend/resume is ok and the brightness consistent.
However, when on battery power a resume comes back with a very dim display and max_brightness is set to 1025. Keys work for adjusting brightness but do not get more than very dim.
Attempting to exceed the now lower max_value results in:
echo 1026 > /sys/class/backlight/nv_backlight/brightness 
-bash: echo: write error: Invalid argument
(attempted writing large value to max_brightness results in permission denied)

Version-Release number of selected component (if applicable):
kernel-2.6.38-0.rc4.git0.2.fc15.x86_64
xorg-x11-drv-nouveau-0.0.16-18.20110117git38e8809.fc15.x86_64


How reproducible:
Always.



Steps to Reproduce:
1. Boot, login. 
2. Note /sys/class/backlight/nv_backlight/max_brightness is 1073864551. 
3. Run on battery and suspend/resume. Note dimmed display and changed max_brightness value.
  
Actual results:
Display is dim. Brightness keys go to max but display is still too dark to use.
/sys/class/backlight/nv_backlight/max_brightness is set to 1025

Expected results:
Brightness returns to normal levels. 

Additional info:
Possibly related to https://bugzilla.redhat.com/show_bug.cgi?id=625171
In which case it is the initial max_brightness value is incorrect (but which works).

Comment 1 Greg Crichton 2011-02-15 16:02:57 UTC
Created attachment 478900 [details]
/var/log/messages excerpt after issue

Comment 2 Greg Crichton 2011-02-15 16:03:46 UTC
Created attachment 478901 [details]
Xorg log

Comment 3 Greg Crichton 2011-02-21 12:02:38 UTC
This has been fixed with latest updates.
2.6.38-0.rc5.git1.1.fc15.x86_64

/sys/class/backlight/acpi_video0/max_brightness is now 7
Removing power dims the screen but using keyboard it can be increased to 7.

/sys/class/backlight/nv_backlight is no longer present.


Note You need to log in before you can comment on or make changes to this bug.