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

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Message-ID: <aWe7_hFpmO0E2sJe@aspen.lan>
Date: Wed, 14 Jan 2026 15:53:34 +0000
From: Daniel Thompson <daniel@...cstar.com>
To: tessolveupstream@...il.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 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?


Daniel.