Re: [PATCH 2/2] dt-bindings: leds: document new "power-supply" property

From: Jean-Jacques Hiblot
Date: Thu Jul 25 2019 - 14:05:34 EST


Hi Rob,

On 24/07/2019 18:47, Rob Herring wrote:
On Mon, Jul 08, 2019 at 12:35:47PM +0200, Jean-Jacques Hiblot wrote:
Most of the LEDs are powered by a voltage/current regulator. describing in
the device-tree makes it possible for the LED core to enable/disable it
when needed.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx>
---
Documentation/devicetree/bindings/leds/common.txt | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/common.txt b/Documentation/devicetree/bindings/leds/common.txt
index 70876ac11367..e093a2b7eb90 100644
--- a/Documentation/devicetree/bindings/leds/common.txt
+++ b/Documentation/devicetree/bindings/leds/common.txt
@@ -61,6 +61,11 @@ Optional properties for child nodes:
- panic-indicator : This property specifies that the LED should be used,
if at all possible, as a panic indicator.
+- power-supply : A voltage/current regulator used to to power the LED. When a
+ LED is turned off, the LED core disable its regulator. The
+ same regulator can power many LED (or other) devices. It is
+ turned off only when all of its users disabled it.
Not sure this should be common. It wouldn't apply to cases where we have
an LED controller parent nor gpio and pwm LEDs and those are most cases.

It does make sense for GPIO and PWM bindings if the anode of LED is tied to a regulated voltage and the cathod to the control line.

The same is true for a certain class of true LED controller that do not deliver power but act like current sinks.

JJ


Perhaps what makes sense here is an regulator-led binding.

+
- trigger-sources : List of devices which should be used as a source triggering
this LED activity. Some LEDs can be related to a specific
device and should somehow indicate its state. E.g. USB 2.0
--
2.17.1