Revision d9a047aeffcef5755952d18f2901d8777d84019d authored by Doug Ledford on 09 July 2015, 14:21:08 UTC, committed by Doug Ledford on 14 July 2015, 17:20:15 UTC
There is little chance our memory allocation will fail, so we can combine initializing the work structs with allocating them instead of looping through all of them once to allocate and again to initialize. Then when we need to actually find out if our device is up or in the process of going down, have all of our work structs batched up, take the spin_lock once and only once, and do all of the batch under the one spin_lock invocation instead of incurring all of the locked memory cycles we would otherwise incur to take/release the spin_lock over and over again. Signed-off-by: Doug Ledford <dledford@redhat.com>
1 parent 9bbf282
video-output.txt
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
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