On Wed, Mar 20, 2013 at 12:00:10PM -0600, Stephen Warren wrote: > On 03/19/2013 12:59 PM, Andrew Chew wrote: > > Many backlights need to be explicitly enabled. Typically, this is done > > with a GPIO. For flexibility, we generalize the enable mechanism to a > > regulator. > > > > If an enable regulator is not needed, then a dummy regulator can be given > > to the backlight driver. If a GPIO is used to enable the backlight, > > then a fixed regulator can be instantiated to control the GPIO. > > > > The backlight enable regulator can be specified in the device tree node > > for the backlight, or can be done with legacy board setup code in the > > usual way. > > > diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > > index 1e4fc72..7e2e089 100644 > > --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > > +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > > @@ -10,6 +10,11 @@ Required properties: > > last value in the array represents a 100% duty cycle (brightest). > > - default-brightness-level: the default brightness level (index into the > > array defined by the "brightness-levels" property) > > + - enable-supply: A phandle to the regulator device tree node. This > > + regulator will be turned on and off as the pwm is enabled and disabled. > > + Many backlights are enabled via a GPIO. In this case, we instantiate > > + a fixed regulator and give that to enable-supply. If a regulator > > + is not needed, then provide a dummy fixed regulator. > > "enable" doesn't seem like the right name here; if this really is an > "enable" input, then it's not a regulator. If you're calling it "enable" > because the regulator is usually controlled by a GPIO that enables it, > then what you really have is a regulator that provides power to the > backlight, and the method that you enable that regulator is irrelevant. > > Put another way, wouldn't "power" be a better name, thus making the > property "power-supply"? Although that property name migth be considered > to have some negative correlation with other concepts, so if people > object to that, perhaps e.g. "vdd-supply"? "power" sounds like a reasonable name to me. Thierry
Attachment:
pgpM7Qd86bk7j.pgp
Description: PGP signature
