Re: [PATCH v2 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs

On 23/01/2026 12:11, tessolveupstream@gmail.com wrote:

On 20-01-2026 20:01, Krzysztof Kozlowski wrote:

quoted

On 20/01/2026 13:50, Sudarshan Shetty wrote:

quoted

Update the gpio-backlight binding to support configurations that require
more than one GPIO for enabling/disabling the backlight.

Why? Which devices need it? How a backlight would have three enable
GPIOs? I really do not believe, so you need to write proper hardware
justification.

To clarify our hardware setup: 
the panel requires one GPIO for the backlight enable signal, and it 
also has a PWM input. Since the QCS615 does not provide a PWM controller 
for this use case, the PWM input is connected to a GPIO that is driven 
high to provide a constant 100% duty cycle, as explained in the link 
below.
https://lore.kernel.org/all/20251028061636.724667-1-tessolveupstream@gmail.com/T/#m93ca4e5c7bf055715ed13316d91f0cd544244cf5 (local)

That's not an enable gpio, but PWM.

You write bindings for this device, not for something else - like your
board.

quoted

quoted

Signed-off-by: Sudarshan Shetty <redacted>
---
 .../leds/backlight/gpio-backlight.yaml        | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
index 584030b6b0b9..4e4a856cbcd7 100644
--- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
+++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml

@@ -16,8 +16,18 @@ properties:
     const: gpio-backlight
 
   gpios:
-    description: The gpio that is used for enabling/disabling the backlight.
-    maxItems: 1
+    description: |
+      The gpio that is used for enabling/disabling the backlight.
+      Multiple GPIOs can be specified for panels that require several
+      enable signals. All GPIOs are controlled together.
+    type: array

There is no such syntax in the bindings, from where did you get it? Type
is already defined.

items:
  minItems: 1
  maxItems: 3

quoted

+    minItems: 1
+    items:
+      type: array
+      minItems: 3
+      maxItems: 3
+      items:
+        type: integer

All this is some odd stuff - just to be clear, don't send us LLM output.
I don't want to waste my time to review microslop.

Was it done with help of Microslop?

I understand now that the schema changes I proposed were not correct, 

How such code could be even created... Just in case, do you understand
that Microslop and LLM is waste of our time?

and I will address this in the next patch series. My intention was to 
check whether the gpio-backlight binding could support more than one 
enable-type GPIO. 
Could you please advise what would be an appropriate maximum number of 
GPIOs for gpio-backlight in such a scenario? For example, would allowing 
2 GPIOs be acceptable, or should this case be handled in a different way?

We have plenty of examples for this, but anyway you won't need it
because this is not an enable GPIO.

Best regards,
Krzysztof