Re: [PATCH RESEND 02/16] Documentation: dt-bindings: backlight: add TI LMU backlight binding information

From: Kim, Milo
Date: Tue Nov 03 2015 - 02:13:35 EST

On 11/3/2015 12:02 AM, Rob Herring wrote:
On Sun, Nov 1, 2015 at 11:24 PM, Milo Kim <> wrote:
LM3532, LM3631, LM3632, LM3633, LM3695 and LM3697 use common dt-bindings
for describing device.

Cc: devicetree@xxxxxxxxxxxxxxx
Cc: Jingoo Han <jingoohan1@xxxxxxxxx>
Cc: Lee Jones <lee.jones@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Milo Kim <>
.../bindings/video/backlight/ti-lmu-backlight.txt | 67 ++++++++++++++++++++++

Please move to bindings/leds/backlight/

There are backlight bindings under video/backlight. I'd like to know why this 'led' location is preferred. My guess is most of properties are from common LED properties. Any other reasons?

1 file changed, 67 insertions(+)
create mode 100644 Documentation/devicetree/bindings/video/backlight/ti-lmu-backlight.txt

diff --git a/Documentation/devicetree/bindings/video/backlight/ti-lmu-backlight.txt b/Documentation/devicetree/bindings/video/backlight/ti-lmu-backlight.txt
new file mode 100644
index 0000000..27b0036
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/backlight/ti-lmu-backlight.txt
@@ -0,0 +1,67 @@
+TI LMU backlight device tree bindings
+Required properties:
+ - compatible: Should be one of lists below.
+ "ti,lm3532-backlight"
+ "ti,lm3631-backlight"
+ "ti,lm3632-backlight"
+ "ti,lm3633-backlight"
+ "ti,lm3695-backlight"
+ "ti,lm3697-backlight"
+Optional properties:
+ There are two backlight control mode. One is I2C, the other is PWM mode.
+ Following properties are only specified in PWM mode.
+ Please note that LMU backlight device can have only one PWM channel.
+ - pwms: OF device-tree PWM specification.
+ - pwm-names: a list of names for the PWM devices specified in the "pwms"
+ property.
+ For the PWM user nodes, please refer to [1].
+Child nodes:
+ LMU backlight is represented as sub-nodes of the TI LMU device [2].
+ So, LMU backlight should have more than one backlight child node.
+ Each node exactly matches with backlight control bank configuration.
+ Maximum numbers of child nodes depend on the device.
+ 1 = LM3631, LM3632, LM3695
+ 2 = LM3633, LM3697
+ 3 = LM3532
+ Required property of a child node:
+ - hvled1-used, hvled2-used, hvled3-used:
+ High voltage backlight strings configuration. Type is <boolean>.
+ Please describe which output backlight string is used.
+ Please refer to the datasheets [3].

Use led-sources.


+ Optional properties of a child node:
+ - backlight-name: Name string for backlight device identification.
+ It is used for creating backlight sysfs,
+ /sys/class/backlight/<backlight-name>/.

Use label.

Got it.

+ - backlight-max-microamp: Max current setting. Type is <u32>.
+ Unit is microampere.
+ Range is from 5000 to 30000.

Use led-max-microamp


+ - initial-brightness: Backlight initial brightness value. Type is <u32>.
+ It is set as soon as backlight device is created.
+ 0 ~ 2047 = LM3631, LM3632, LM3633, LM3695 and LM3697
+ 0 ~ 255 = LM3532

Use default-brightness-level

I'll update the bindings and drivers based on your review. Many thanks!

Best regards,
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