[PATCH] dt-bindings: pwm: Convert NXP PCA9685 PWM controller to DT schema

[PATCH] dt-bindings: pwm: Convert NXP PCA9685 PWM controller to DT schema

[Jeremy Dean]

Convert the NXP PCA9685 PWM controller binding to DT schema format.

Changes from the text binding:

Document the 'reg' property and make it required. It was missing
from the text binding, although the example used it and the device
cannot work without the I2C address.

Rename the example node to the generic 'pwm', as required by
pwm.yaml.

Describe both cells of the PWM specifier, and state that 'invert'
and 'open-drain' apply to all outputs, as per the datasheet (INVRT
and OUTDRV bits in MODE2).

Assisted-by: LLM
Signed-off-by: Jeremy Dean <deaner92@yahoo.com>
---
The schema was generated with an AI assistant (Claude).
I verified the properties against the driver source, the PCA9685
datasheet, and the text binding. Passes make dt_binding_check.
 .../bindings/pwm/nxp,pca9685-pwm.txt          | 27 --------
 .../bindings/pwm/nxp,pca9685-pwm.yaml         | 62 +++++++++++++++++++
 2 files changed, 62 insertions(+), 27 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.txt
 create mode 100644 Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml

diff --git a/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.txt b/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.txt
deleted file mode 100644
index f21b55c95738..000000000000
--- a/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.txt
+++ /dev/null
@@ -1,27 +0,0 @@
-NXP PCA9685 16-channel 12-bit PWM LED controller
-================================================
-
-Required properties:
-  - compatible: "nxp,pca9685-pwm"
-  - #pwm-cells: Should be 2. See pwm.yaml in this directory for a description of
-    the cells format.
-    The index 16 is the ALLCALL channel, that sets all PWM channels at the same
-    time.
-
-Optional properties:
-  - invert (bool): boolean to enable inverted logic
-  - open-drain (bool): boolean to configure outputs with open-drain structure;
-		       if omitted use totem-pole structure
-
-Example:
-
-For LEDs that are directly connected to the PCA, the following setting is
-applicable:
-
-pca: pca@41 {
-	compatible = "nxp,pca9685-pwm";
-	#pwm-cells = <2>;
-	reg = <0x41>;
-	invert;
-	open-drain;
-};
diff --git a/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml b/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml
new file mode 100644
index 000000000000..36b312ac0be9
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/nxp,pca9685-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP PCA9685 16-channel 12-bit PWM LED controller
+
+maintainers:
+  - Jeremy Clifton <deaner92@yahoo.com>
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    const: nxp,pca9685-pwm
+
+  reg:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 2
+    description:
+      The first cell is the PWM channel index, from 0 to 15, or 16 for the
+      ALLCALL channel, which sets all PWM channels at the same time. The
+      second cell is the PWM period in nanoseconds.
+
+  invert:
+    type: boolean
+    description:
+      Invert the logic state of all outputs (INVRT bit in the MODE2
+      register). The setting applies to the whole chip, not to individual
+      channels, and is typically used when the outputs drive an external
+      driver stage.
+
+  open-drain:
+    type: boolean
+    description:
+      Configure all outputs with an open-drain structure (OUTDRV bit in the
+      MODE2 register). If omitted, the outputs use a totem-pole structure.
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        pwm@41 {
+            compatible = "nxp,pca9685-pwm";
+            reg = <0x41>;
+            #pwm-cells = <2>;
+            invert;
+            open-drain;
+        };
+    };

base-commit: bf1ee2bd5c2da8992f33c8950ef194aaff74ed6c
-- 
2.43.0

Re: [PATCH] dt-bindings: pwm: Convert NXP PCA9685 PWM controller to DT schema

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] dt-bindings: pwm: missing #pwm-cells in required properties
- [Low] dt-bindings: pwm: hallucinated maintainer name in YAML schema
--

commit 2d85be96eb45879405596ef1a5131c2b3425b8ed
Author: Jeremy Dean <deaner92@yahoo.com>

dt-bindings: pwm: Convert NXP PCA9685 PWM controller to DT schema

Convert the NXP PCA9685 PWM controller binding to DT schema format. The
conversion documents the reg property and makes it required, updates the
example node, and describes the PWM specifier cells and properties.

> diff --git a/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml b/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml
> new file mode 100644
> index 0000000000000..36b312ac0be95
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/nxp,pca9685-pwm.yaml
> @@ -0,0 +1,62 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pwm/nxp,pca9685-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP PCA9685 16-channel 12-bit PWM LED controller
> +
> +maintainers:
> +  - Jeremy Clifton <deaner92@yahoo.com>

[Severity: Low]
Is this the correct maintainer name? It looks like the name listed here 
does not match the name of the patch submitter. Could this result in 
incorrect attribution and metadata parsing by get_maintainer.pl?

[ ... ]

> +required:
> +  - compatible
> +  - reg

[Severity: Medium]
Should #pwm-cells be included in this required block? 

The original text binding correctly mandated #pwm-cells since the PCA9685 
acts as a PWM provider. Omitting it from the required list here reduces 
schema validation coverage, allowing device trees that are missing the 
property to silently pass.

> +
> +unevaluatedProperties: false

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261006033518.34332-1-deaner92@yahoo.com?part=1

Re: [PATCH] dt-bindings: pwm: Convert NXP PCA9685 PWM controller to DT schema

[Krzysztof Kozlowski]

On Tue, Oct 06, 2026 at 03:35:18AM +0000, Jeremy Dean wrote:
> 
> Assisted-by: LLM
> Signed-off-by: Jeremy Dean <deaner92@yahoo.com>

...

> +maintainers:
> +  - Jeremy Clifton <deaner92@yahoo.com>

I think we are done on these hallucinations.

There is little point for beginner contributors to send us DT binding
conversions generated by LLM.

Best regards,
Krzysztof

Re: [PATCH] dt-bindings: pwm: Convert NXP PCA9685 PWM controller to DT schema

[Jeremy Clifton]

Hello Krzysztof + all,

Dean is a middle name I use in place of my surname, Clifton, so both
names are mine. I should have used the same one in both places; that
mismatch is my mistake.

The goal was to bring this binding up to par with the rest of the PWM
bindings, so that device trees and overlays using the PCA9685 can be
validated with dtbs_check. It's a common chip in beginner robotics
projects, and the schema means the beginners who run dtbs_check can be
sure their DTS has no mismatches.

For reference, I put together a template for DT schemas:
https://drive.google.com/file/d/183T6W73x45-0WRpo372I1OMeQZop-XzQ/view?usp=drive_link

and a requirements document which could be a starter guide for someone 
putting
together such a schema:
https://drive.google.com/file/d/1K_pfVIZ6u9GjD5tL4TJ40qOHM-_eWe4O/view?usp=sharing

Look out for a v2 with zero hallucination sashiko flags (My middle name 
is Dean).

Jeremy

On 10/9/26 5:36 AM, Krzysztof Kozlowski wrote:
> On Tue, Oct 06, 2026 at 03:35:18AM +0000, Jeremy Dean wrote:
>>
>> Assisted-by: LLM
>> Signed-off-by: Jeremy Dean <deaner92@yahoo.com>
> 
> ...
> 
>> +maintainers:
>> +  - Jeremy Clifton <deaner92@yahoo.com>
> 
> I think we are done on these hallucinations.
> 
> There is little point for beginner contributors to send us DT binding
> conversions generated by LLM.
> 
> Best regards,
> Krzysztof