Pavel,

On 10/07/2019 21:13, Pavel Machek wrote:
On Wed 2019-07-10 14:39:31, Jean-Jacques Hiblot wrote:
Add DT binding for led-backlight.

Signed-off-by: Jean-Jacques Hiblot <jjhib...@ti.com>
---
  .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
  1 file changed, 28 insertions(+)
  create mode 100644 
Documentation/devicetree/bindings/leds/backlight/led-backlight.txt

diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt 
b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
new file mode 100644
index 000000000000..0444eec8efe1
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
@@ -0,0 +1,28 @@
+led-backlight bindings
+
+This binding is used to describe a basic backlight device made of
LEDs.
Ok.

+It can also be used to describe a backlight device controlled by the output of
+a LED driver.
? The LED driver should better be driving some LEDs...

Well. we are dependent of the board design. If a board designer decided to control a backlight with a LED-controller, then we have to deal with it.

In practice there are a lot of LED drivers that actually drive the LEDs using PWMs and can be used for this purpose.

JJ


+Required properties:
+  - compatible: "led-backlight"
+  - leds: a list of LEDs
+
+Optional properties:
+  - brightness-levels: Array of distinct brightness levels. The levels must be
+                       in the range accepted by the underlying LED devices.
+                       This is used to translate a backlight brightness level
+                       into a LED brightness level. if not provided, the
+                       identity mapping is used.
"If it is not"
                                                                        Pavel

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