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[PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs

Sudarshan Shetty posted 2 patches 1 month ago
[PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs
Posted by Sudarshan Shetty 1 month ago 
Update the gpio-backlight binding to support configurations that require
more than one GPIO for enabling/disabling the backlight.

Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
---
 .../bindings/leds/backlight/gpio-backlight.yaml      | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
index 584030b6b0b9..1483ce4a3480 100644
--- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
+++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
@@ -17,7 +17,8 @@ properties:
 
   gpios:
     description: The gpio that is used for enabling/disabling the backlight.
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
 
   default-on:
     description: enable the backlight at boot.
@@ -38,4 +39,13 @@ examples:
         default-on;
     };
 
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    backlight {
+      compatible = "gpio-backlight";
+      gpios = <&gpio3 4 GPIO_ACTIVE_HIGH>,
+              <&gpio3 5 GPIO_ACTIVE_HIGH>;
+      default-on;
+    };
+
 ...
-- 
2.34.1
Re: [PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs
Posted by Daniel Thompson 1 month ago 
On Mon, Jan 05, 2026 at 02:21:19PM +0530, Sudarshan Shetty wrote:
> Update the gpio-backlight binding to support configurations that require
> more than one GPIO for enabling/disabling the backlight.
>
> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
> ---
>  .../bindings/leds/backlight/gpio-backlight.yaml      | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> index 584030b6b0b9..1483ce4a3480 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> @@ -17,7 +17,8 @@ properties:
>
>    gpios:
>      description: The gpio that is used for enabling/disabling the backlight.
> -    maxItems: 1
> +    minItems: 1
> +    maxItems: 2

Why 2?


Daniel.
Re: [PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs
Posted by tessolveupstream@gmail.com 3 weeks, 4 days ago 

On 05-01-2026 15:25, Daniel Thompson wrote:
> On Mon, Jan 05, 2026 at 02:21:19PM +0530, Sudarshan Shetty wrote:
>> Update the gpio-backlight binding to support configurations that require
>> more than one GPIO for enabling/disabling the backlight.
>>
>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
>> ---
>>  .../bindings/leds/backlight/gpio-backlight.yaml      | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
>> index 584030b6b0b9..1483ce4a3480 100644
>> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
>> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
>> @@ -17,7 +17,8 @@ properties:
>>
>>    gpios:
>>      description: The gpio that is used for enabling/disabling the backlight.
>> -    maxItems: 1
>> +    minItems: 1
>> +    maxItems: 2
> 
> Why 2?
> 

In the current design, the LVDS panel has a single backlight that
is controlled by two GPIOs. Initially, It described as two separate 
backlight devices using the same gpio-backlight driver, since the 
existing driver supports only one GPIO per instance.

So the maintainer suggested to extend the gpio-backlight driver 
and bindings to support multiple GPIOs.
https://lore.kernel.org/all/q63bdon55app4gb2il5e7skyc6z2amcnaiqbqlhen7arkxphtb@3jejbelji2ti/
> 
> Daniel.
Re: [PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs
Posted by Daniel Thompson 3 weeks, 2 days ago 
On Tue, Jan 13, 2026 at 10:15:53AM +0530, tessolveupstream@gmail.com wrote:
>
>
> On 05-01-2026 15:25, Daniel Thompson wrote:
> > On Mon, Jan 05, 2026 at 02:21:19PM +0530, Sudarshan Shetty wrote:
> >> Update the gpio-backlight binding to support configurations that require
> >> more than one GPIO for enabling/disabling the backlight.
> >>
> >> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
> >> ---
> >>  .../bindings/leds/backlight/gpio-backlight.yaml      | 12 +++++++++++-
> >>  1 file changed, 11 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> >> index 584030b6b0b9..1483ce4a3480 100644
> >> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> >> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> >> @@ -17,7 +17,8 @@ properties:
> >>
> >>    gpios:
> >>      description: The gpio that is used for enabling/disabling the backlight.
> >> -    maxItems: 1
> >> +    minItems: 1
> >> +    maxItems: 2
> >
> > Why 2?
> >
>
> In the current design, the LVDS panel has a single backlight that
> is controlled by two GPIOs. Initially, It described as two separate
> backlight devices using the same gpio-backlight driver, since the
> existing driver supports only one GPIO per instance.
>
> So the maintainer suggested to extend the gpio-backlight driver
> and bindings to support multiple GPIOs.
> https://lore.kernel.org/all/q63bdon55app4gb2il5e7skyc6z2amcnaiqbqlhen7arkxphtb@3jejbelji2ti/

Right. So, once we support multiple GPIOs then why limit it to 2?


Daniel.
Re: [PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs
Posted by tessolveupstream@gmail.com 2 weeks, 5 days ago 

On 14-01-2026 21:23, Daniel Thompson wrote:
> On Tue, Jan 13, 2026 at 10:15:53AM +0530, tessolveupstream@gmail.com wrote:
>>
>>
>> On 05-01-2026 15:25, Daniel Thompson wrote:
>>> On Mon, Jan 05, 2026 at 02:21:19PM +0530, Sudarshan Shetty wrote:
>>>> Update the gpio-backlight binding to support configurations that require
>>>> more than one GPIO for enabling/disabling the backlight.
>>>>
>>>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
>>>> ---
>>>>  .../bindings/leds/backlight/gpio-backlight.yaml      | 12 +++++++++++-
>>>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
>>>> index 584030b6b0b9..1483ce4a3480 100644
>>>> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
>>>> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
>>>> @@ -17,7 +17,8 @@ properties:
>>>>
>>>>    gpios:
>>>>      description: The gpio that is used for enabling/disabling the backlight.
>>>> -    maxItems: 1
>>>> +    minItems: 1
>>>> +    maxItems: 2
>>>
>>> Why 2?
>>>
>>
>> In the current design, the LVDS panel has a single backlight that
>> is controlled by two GPIOs. Initially, It described as two separate
>> backlight devices using the same gpio-backlight driver, since the
>> existing driver supports only one GPIO per instance.
>>
>> So the maintainer suggested to extend the gpio-backlight driver
>> and bindings to support multiple GPIOs.
>> https://lore.kernel.org/all/q63bdon55app4gb2il5e7skyc6z2amcnaiqbqlhen7arkxphtb@3jejbelji2ti/
> 
> Right. So, once we support multiple GPIOs then why limit it to 2?
> 

Okay, got the point. I'm removing the maxItems constraint entirely 
to allow any number of GPIOs as below:

diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
index 1483ce4a3480..82698519daff 100644
--- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
+++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
@@ -16,9 +16,11 @@ properties:
     const: gpio-backlight

   gpios:
-    description: The gpio that is used for enabling/disabling the backlight.
+    description: |
+      The gpio that is used for enabling/disabling the backlight.
+      Multiple GPIOs can be specified for panels that require several
+      enable signals.
     minItems: 1
-    maxItems: 2

   default-on:
     description: enable the backlight at boot.

Does this approach work for you?
> 
> Daniel.
Re: [PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs
Posted by Daniel Thompson 2 weeks, 4 days ago 
On Sun, Jan 18, 2026 at 10:18:32PM +0530, tessolveupstream@gmail.com wrote:
> On 14-01-2026 21:23, Daniel Thompson wrote:
> > On Tue, Jan 13, 2026 at 10:15:53AM +0530, tessolveupstream@gmail.com wrote:
> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> index 1483ce4a3480..82698519daff 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> @@ -16,9 +16,11 @@ properties:
>      const: gpio-backlight
>
>    gpios:
> -    description: The gpio that is used for enabling/disabling the backlight.
> +    description: |
> +      The gpio that is used for enabling/disabling the backlight.
> +      Multiple GPIOs can be specified for panels that require several
> +      enable signals.
>      minItems: 1
> -    maxItems: 2
>
>    default-on:
>      description: enable the backlight at boot.
>
> Does this approach work for you?

I think so... but I'd rather just review a v2 patch than this kind of
meta-patch.


Daniel.

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