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"? -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
