Bug Affects:
Thinkpad T41 (and possibly other models)
Kernels:
2.6.32-18 (Not bugged)
2.6.32-19 (Bugged)
2.6.32-20 (Bugged)
Symptoms:
- Display backlight brightness changes to the lowest value once kde starts to load after logging in from kdm (once hal starts)
- Same happens when switching to X session from tty
- Cannot change display brightness with Powerdevil (kde's power manager), any change dims display
- thinkpad extra buttons for changing backlight brightness (Fn+Home, Fn+End) work normally.
Cause:
Difference in lshal output with nonbugged *-18 and bugged *-20 kernels
Workaround:
1. Create a custom hal policy file for forcing laptop_panel.num_levels value to 8:
file '/etc/hal/fdi/policy/10-thinkpad-backlight' contents:
2. Relog to restart hal
Remaining Issues:
Powerdevil display brightness slider still doesn't work as expected, but other issues should be fixed.
This is just a workaround and not a definite fix (seems something was changed between *-18 and *-19 kernel, and everything hasn't catched up with the change yet)
Thinkpad T41 (and possibly other models)
Kernels:
2.6.32-18 (Not bugged)
2.6.32-19 (Bugged)
2.6.32-20 (Bugged)
Symptoms:
- Display backlight brightness changes to the lowest value once kde starts to load after logging in from kdm (once hal starts)
- Same happens when switching to X session from tty
- Cannot change display brightness with Powerdevil (kde's power manager), any change dims display
- thinkpad extra buttons for changing backlight brightness (Fn+Home, Fn+End) work normally.
Cause:
Difference in lshal output with nonbugged *-18 and bugged *-20 kernels
165c149
< laptop_panel.num_levels = 8 (0x8) (int)
---
> laptop_panel.num_levels = 1 (0x1) (int)
< laptop_panel.num_levels = 8 (0x8) (int)
---
> laptop_panel.num_levels = 1 (0x1) (int)
1. Create a custom hal policy file for forcing laptop_panel.num_levels value to 8:
file '/etc/hal/fdi/policy/10-thinkpad-backlight' contents:
<?xml version="1.0" encoding="ISO-8859-1"?> <!-- -*- SGML -*- -->
<deviceinfo version="0.2">
<device>
<match key="info.category" string="laptop_panel">
<match key="linux.sysfs_path" suffix="/backlight/thinkpad_screen">
<merge key="laptop_panel.num_levels" type="int">8</merge>
</match>
</match>
</device>
</deviceinfo>
<deviceinfo version="0.2">
<device>
<match key="info.category" string="laptop_panel">
<match key="linux.sysfs_path" suffix="/backlight/thinkpad_screen">
<merge key="laptop_panel.num_levels" type="int">8</merge>
</match>
</match>
</device>
</deviceinfo>
Remaining Issues:
Powerdevil display brightness slider still doesn't work as expected, but other issues should be fixed.
This is just a workaround and not a definite fix (seems something was changed between *-18 and *-19 kernel, and everything hasn't catched up with the change yet)