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

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Message-ID: <95a49665-f379-48a7-a2b5-d288cdfdc0a8@gmail.com>
Date: Sun, 18 Jan 2026 22:18:32 +0530
From: tessolveupstream@...il.com
To: Daniel Thompson <daniel@...cstar.com>
Cc: lee@...nel.org, danielt@...nel.org, jingoohan1@...il.com, deller@....de,
 pavel@...nel.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
 linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-bindings: backlight: gpio-backlight: allow
 multiple GPIOs



On 14-01-2026 21:23, Daniel Thompson wrote:
> On Tue, Jan 13, 2026 at 10:15:53AM +0530, tessolveupstream@...il.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@...il.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.