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author | Felipe Contreras <felipe.contreras@gmail.com> | 2013-08-03 23:00:25 +0200 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-08-04 23:45:39 +0200 |
commit | b3b301c5fed8a0868e56c98b922cb0c881b3857d (patch) | |
tree | add3a807e37d55993d7ae9ea74fff062dae5da32 /drivers/acpi/proc.c | |
parent | c095ba7224d8edc71dcef0d655911399a8bd4a3f (diff) |
ACPI / video: improve quirk check in acpi_video_bqc_quirk()
If the _BCL package ordering is descending, the first level
(br->levels[2]) is likely to be 0, and if the number of levels
matches the number of steps, we might confuse a returned level to
mean the index.
For example:
current_level = max_level = 100
test_level = 0
returned level = 100
In this case 100 means the level, not the index, and _BCM failed.
Still, if the _BCL package ordering is descending, the index of
level 0 is also 100, so we assume _BQC is indexed, when it's not.
This causes all _BQC calls to return bogus values causing weird
behavior from the user's perspective. For example:
xbacklight -set 10; xbacklight -set 20;
would flash to 90% and then slowly down to the desired level (20).
The solution is simple; test anything other than the first level
(e.g. 1).
[rjw: Changelog]
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/proc.c')
0 files changed, 0 insertions, 0 deletions