On 25/08/15 16:39, Jacek Anaszewski wrote:

quoted

+Example:
+
+    backlight {
+        compatible = "led-backlight";
+        leds = <&backlight_led>;
+
+        brightness-levels = <0 4 8 16 32 64 128 255>;

brightness level is not a suitable unit for describing LED brightness
in a Device Tree, as it is not a physical unit. We have led-max-microamp
property for this, expressed in microamperes, please refer to [0] from
linux-next.

Hmm, ok, but what should the driver do with microamperes? As far as I
see, "enum led_brightness" (which is between 0-255) is used to set the
brightness to LEDs. I don't see any function accepting microamperes.

quoted

+        default-brightness-level = <6>;

This also should be microamperes.

This is an index to the above brightness-levels array. It's not LED
brightness, but backlight brightness, between 0 and
ARRAY_SIZE(brightness-levels) - 1.

 Tomi