## page was renamed from Kernel/Reference/fwts/brightness
== Firmware Test Suite - brightness test ==

This interactive test sanity checks the operation of the ACPI display brightness levels found on netbooks and laptops.  Several tests are performed:

 * Check for maximum and actual brightness. 
 * Change the brightness.
 * Observe all brightness changes.
 * Observe min, max brightness changes.
 * Check brightness hotkeys.

The test will change the brightness levels and ask the observer if the levels have been changed. It will also
ask the tester to press the brightness up/down hotkeys to see if these change the brightness levels.

=== Examples: ===

{{{
fwts brightness - 
}}}

..runs the test on your machine and dumps the output to stdout. This test requires user interaction.

== Explanation of test results ==

Certain test results may require a little more explanation. This section will try and give some context to specific test failures.

||Error ID||Explanation||
||Backlight``No``Path||/sys/devices/virtual/backlight does not exist. Cannot test.||
||Brightness``Max``Test1||The maximum brightness is invalid.||
||Brightness``Outof``Range||The maximum brightness is out of range.||
||Brightness``Max``Test2||The maximum brightness is invalid.||
||Brightness``Mismatch||The actual brightness read does not match the brightnesss level just set for backlight.||
||Brightness``Max``Test3||The maximum brightness is invalid.||
||Brightness``Dim``Level||Could not set to the dimmest level.||
||Brightness``Bright``Level||Could not set to the brightest level.||
||Brightness``Max``Test4||The maximum brightness is invalid.||
||Brightness``No``Dimming||Could not observe brightness levels dim.||
||Brightness``No``Hot``Key||Did not detect any ACPI hotkey events.||
||Brightness``No``Increase||Pressing the ACPI brightness up key did not increase the brightness level.||
||Brightness``No``Decrease||Pressing the ACPI brightness down key did not decrease the brightness level.||