On 20-01-2026 20:01, Krzysztof Kozlowski wrote:
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)
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,
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?
Best regards,
Krzysztof