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-rw-r--r--Documentation/video-output.txt34
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+
+ Video Output Switcher Control
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ 2006 luming.yu@intel.com
+
+The output sysfs class driver provides an abstract video output layer that
+can be used to hook platform specific methods to enable/disable video output
+device through common sysfs interface. For example, on my IBM ThinkPad T42
+laptop, The ACPI video driver registered its output devices and read/write
+method for 'state' with output sysfs class. The user interface under sysfs is:
+
+linux:/sys/class/video_output # tree .
+.
+|-- CRT0
+| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+| |-- state
+| |-- subsystem -> ../../../class/video_output
+| `-- uevent
+|-- DVI0
+| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+| |-- state
+| |-- subsystem -> ../../../class/video_output
+| `-- uevent
+|-- LCD0
+| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+| |-- state
+| |-- subsystem -> ../../../class/video_output
+| `-- uevent
+`-- TV0
+ |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+ |-- state
+ |-- subsystem -> ../../../class/video_output
+ `-- uevent
+