[2/2] dt-bindings: leds: document new "power-supply" property
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Message ID 20190708103547.23528-3-jjhiblot@ti.com
State Changes Requested
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  • leds: Add control of the voltage/current regulator to the LED core
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Jean-Jacques Hiblot July 8, 2019, 10:35 a.m. UTC
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@ti.com>
---
 Documentation/devicetree/bindings/leds/common.txt | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Dan Murphy July 12, 2019, 6:38 p.m. UTC | #1
JJ

On 7/8/19 5:35 AM, 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.

This should be patch 1.


> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> ---
>   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.
> +
>   - 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


Do you have an example update?

Dan
Rob Herring July 24, 2019, 4:47 p.m. UTC | #2
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@ti.com>
> ---
>  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.

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
>
Jean-Jacques Hiblot July 25, 2019, 11:08 a.m. UTC | #3
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@ti.com>
>> ---
>>   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
>>
Daniel Thompson July 26, 2019, 10:06 a.m. UTC | #4
On Thu, Jul 25, 2019 at 01:08:46PM +0200, Jean-Jacques Hiblot wrote:
> 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@ti.com>
> > > ---
> > >   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.

You didn't comment on this alternative... and I confess I'm not quite
sure what Rob means by a regulator-led binding so I can't really comment
either.

Rob, is there any analogous example for a regulator-<something-else> binding
to compare with?


Daniel.

> > 
> > > +
> > >   - 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
> > >
Rob Herring July 26, 2019, 10:44 p.m. UTC | #5
On Fri, Jul 26, 2019 at 4:06 AM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Thu, Jul 25, 2019 at 01:08:46PM +0200, Jean-Jacques Hiblot wrote:
> > 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@ti.com>
> > > > ---
> > > >   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.

Okay. Is one of those your case, or you only have regulator control?
The latter would need a new binding. If you want to use power-supply
with either GPIO and PWM LED bindings, then it should still be listed
in those as an applicable property.

> > 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.
>
> You didn't comment on this alternative... and I confess I'm not quite
> sure what Rob means by a regulator-led binding so I can't really comment
> either.
>
> Rob, is there any analogous example for a regulator-<something-else> binding
> to compare with?

regulator-haptic is the only one I found in a quick search.

Rob

Patch
diff mbox series

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.
+
 - 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