diff options
author | Matthew Garrett <mjg@redhat.com> | 2011-03-22 19:30:21 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-22 20:43:59 -0400 |
commit | bb7ca747f8d6243b3943c5b133048652020f4a50 (patch) | |
tree | b40e879a7b26e3763aea2af2d4dd9079483de11e /Documentation/ABI/stable | |
parent | ccd7510fd8dea5b4b2af87fb2aef2ebd6b23b76b (diff) |
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/ABI/stable')
-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> | |||
34 | Description: | 34 | Description: |
35 | Maximum brightness for <backlight>. | 35 | Maximum brightness for <backlight>. |
36 | Users: HAL | 36 | Users: HAL |
37 | |||
38 | What: /sys/class/backlight/<backlight>/type | ||
39 | Date: September 2010 | ||
40 | KernelVersion: 2.6.37 | ||
41 | Contact: Matthew Garrett <mjg@redhat.com> | ||
42 | Description: | ||
43 | The type of interface controlled by <backlight>. | ||
44 | "firmware": The driver uses a standard firmware interface | ||
45 | "platform": The driver uses a platform-specific interface | ||
46 | "raw": The driver controls hardware registers directly | ||
47 | |||
48 | In the general case, when multiple backlight | ||
49 | interfaces are available for a single device, firmware | ||
50 | control should be preferred to platform control should | ||
51 | be preferred to raw control. Using a firmware | ||
52 | interface reduces the probability of confusion with | ||
53 | the hardware and the OS independently updating the | ||
54 | backlight state. Platform interfaces are mostly a | ||
55 | holdover from pre-standardisation of firmware | ||
56 | interfaces. | ||