On 08/25/2015 05:41 PM, Tomi Valkeinen wrote:
On 25/08/15 16:39, Jacek Anaszewski wrote:
+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.
This is implementation detail. You can convert microamperes to
enum led_brightness in the driver. Please refer to the discussion [1].
+ 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.
You could skip "-level" postfix and have default brightness
in microamperes.
[1] http://www.spinics.net/lists/linux-leds/msg03416.html
--
Best Regards,
Jacek Anaszewski
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