Bug 677694

Summary: /sys/class/backlight/nv_backlight/max_brightness is set to lower value after suspend on battery power giving dim display
Product: [Fedora] Fedora Reporter: Greg Crichton <gcrichton>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: unspecified    
Version: rawhideCC: gansalmon, gcrichton, itamar, jonathan, kernel-maint, madhu.chinakonda
Target Milestone: ---   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-02-21 12:02:38 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
lspci -vv -nn -d 10de:0a29
none
/var/log/messages excerpt after issue
none
Xorg log none

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.