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| author |   Matthew Garrett <mjg@redhat.com> | 2011-03-22 16:30:21 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-22 17:43:59 -0700 |
| commit | bb7ca747f8d6243b3943c5b133048652020f4a50 (patch) | |
| tree | b40e879a7b26e3763aea2af2d4dd9079483de11e /Documentation | |
| parent | drivers/leds/leds-lp5523.c: world-writable engine* sysfs files (diff) | |
| download | linux-dev-bb7ca747f8d6243b3943c5b133048652020f4a50.tar.xz linux-dev-bb7ca747f8d6243b3943c5b133048652020f4a50.zip | |
backlight: add backlight type
There may be multiple ways of controlling the backlight on a given
machine. Allow drivers to expose the type of interface they are
providing, making it possible for userspace to make appropriate policy
decisions.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: David Airlie <airlied@linux.ie>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-class-backlight | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight index 4d637e1c4ff7..70302f370e7e 100644 --- a/Documentation/ABI/stable/sysfs-class-backlight +++ b/Documentation/ABI/stable/sysfs-class-backlight @@ -34,3 +34,23 @@ Contact: Richard Purdie <rpurdie@rpsys.net> Description: Maximum brightness for <backlight>. Users: HAL + +What: /sys/class/backlight/<backlight>/type +Date: September 2010 +KernelVersion: 2.6.37 +Contact: Matthew Garrett <mjg@redhat.com> +Description: + The type of interface controlled by <backlight>. + "firmware": The driver uses a standard firmware interface + "platform": The driver uses a platform-specific interface + "raw": The driver controls hardware registers directly + + In the general case, when multiple backlight + interfaces are available for a single device, firmware + control should be preferred to platform control should + be preferred to raw control. Using a firmware + interface reduces the probability of confusion with + the hardware and the OS independently updating the + backlight state. Platform interfaces are mostly a + holdover from pre-standardisation of firmware + interfaces. |