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| author | Thierry Reding <treding@nvidia.com> | 2013-08-30 12:42:42 +0200 |
|---|---|---|
| committer | Thierry Reding <treding@nvidia.com> | 2014-06-03 15:01:17 +0200 |
| commit | 3d301459a8bd5d63f8910ab8fe16cf3db1c76e9d (patch) | |
| tree | 87b45e36a943deb45ad7adf09c390aefc4064d99 /Documentation | |
| parent | c65cb03c5d75f1f5eb8399bed83ff590a44785c9 (diff) | |
pwm-backlight: Allow backlight to remain disabled on boot
The default for backlight devices is to be enabled immediately when
registering with the backlight core. This can be useful for setups that
use a simple framebuffer device and where the backlight cannot otherwise
be hooked up to the panel.
However, when dealing with more complex setups, such as those of recent
ARM SoCs, this can be problematic. Since the backlight is usually setup
separately from the display controller, the probe order is not usually
deterministic. That can lead to situations where the backlight will be
powered up and the panel will show an uninitialized framebuffer.
Furthermore, subsystems such as DRM have advanced functionality to set
the power mode of a panel. In order to allow such setups to power up the
panel at exactly the right moment, a way is needed to prevent the
backlight core from powering the backlight up automatically when it is
registered.
This commit introduces a new boot_off field in the platform data (and
also implements getting the same information from device tree). When set
the initial backlight power mode will be set to "off".
Signed-off-by: Thierry Reding <treding@nvidia.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt index 764db86d441..65e001a1733 100644 --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt @@ -17,6 +17,7 @@ Optional properties: "pwms" property (see PWM binding[0]) - enable-gpios: contains a single GPIO specifier for the GPIO which enables and disables the backlight (see GPIO binding[1]) + - backlight-boot-off: keep the backlight disabled on boot [0]: Documentation/devicetree/bindings/pwm/pwm.txt [1]: Documentation/devicetree/bindings/gpio/gpio.txt |