The previous description was misleading because this hardware block is not
a PWM generator. It does not generate a signal with a specific frequency
and duty ratio.

Instead, it provides a fixed nanosecond-level adjustment to the rising/
falling edges of an existing signal.

The property name is kept as 'realtek,duty-cycle' rather than being
renamed to strictly preserve Device Tree ABI backward compatibility.

Signed-off-by: Yu-Chun Lin <eleanor.lin@realtek.com>
---
Changes in v3:
- Reverted property name change.
---
 .../bindings/pinctrl/realtek,rtd1315e-pinctrl.yaml         | 7 +++++--
 .../bindings/pinctrl/realtek,rtd1319d-pinctrl.yaml         | 7 +++++--
 .../bindings/pinctrl/realtek,rtd1619b-pinctrl.yaml         | 7 +++++--
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/pinctrl/realtek,rtd1315e-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/realtek,rtd1315e-pinctrl.yaml
index 90bd49d87d2e..2a640e495cc7 100644
--- a/Documentation/devicetree/bindings/pinctrl/realtek,rtd1315e-pinctrl.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/realtek,rtd1315e-pinctrl.yaml
@@ -135,8 +135,11 @@ patternProperties:
 
       realtek,duty-cycle:
         description: |
-          An integer describing the level to adjust output duty cycle, controlling
-          the proportion of positive and negative waveforms in nanoseconds.
+          An integer describing the level to adjust the output pulse width, it
+          provides a fixed nanosecond-level adjustment to the rising/falling
+          edges of an existing signal. It is used for Signal Integrity tuning
+          (adding/subtracting delay to fine-tune the high/low duration), rather
+          than generating a specific PWM frequency.
           Valid arguments are described as below:
           0: 0ns
           2: + 0.25ns
diff --git a/Documentation/devicetree/bindings/pinctrl/realtek,rtd1319d-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/realtek,rtd1319d-pinctrl.yaml
index b6211c8544ca..2136546adec8 100644
--- a/Documentation/devicetree/bindings/pinctrl/realtek,rtd1319d-pinctrl.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/realtek,rtd1319d-pinctrl.yaml
@@ -134,8 +134,11 @@ patternProperties:
 
       realtek,duty-cycle:
         description: |
-          An integer describing the level to adjust output duty cycle, controlling
-          the proportion of positive and negative waveforms in nanoseconds.
+          An integer describing the level to adjust the output pulse width, it
+          provides a fixed nanosecond-level adjustment to the rising/falling
+          edges of an existing signal. It is used for Signal Integrity tuning
+          (adding/subtracting delay to fine-tune the high/low duration), rather
+          than generating a specific PWM frequency.
           Valid arguments are described as below:
           0: 0ns
           2: + 0.25ns
diff --git a/Documentation/devicetree/bindings/pinctrl/realtek,rtd1619b-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/realtek,rtd1619b-pinctrl.yaml
index e88bc649cc73..e8ea1362b16d 100644
--- a/Documentation/devicetree/bindings/pinctrl/realtek,rtd1619b-pinctrl.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/realtek,rtd1619b-pinctrl.yaml
@@ -133,8 +133,11 @@ patternProperties:
 
       realtek,duty-cycle:
         description: |
-          An integer describing the level to adjust output duty cycle, controlling
-          the proportion of positive and negative waveforms in nanoseconds.
+          An integer describing the level to adjust the output pulse width, it
+          provides a fixed nanosecond-level adjustment to the rising/falling
+          edges of an existing signal. It is used for Signal Integrity tuning
+          (adding/subtracting delay to fine-tune the high/low duration), rather
+          than generating a specific PWM frequency.
           Valid arguments are described as below:
           0: 0ns
           2: + 0.25ns
-- 
2.34.1

On Thu, Mar 12, 2026 at 12:30 PM Yu-Chun Lin <eleanor.lin@realtek.com> wrote:

> The previous description was misleading because this hardware block is not
> a PWM generator. It does not generate a signal with a specific frequency
> and duty ratio.
>
> Instead, it provides a fixed nanosecond-level adjustment to the rising/
> falling edges of an existing signal.
>
> The property name is kept as 'realtek,duty-cycle' rather than being
> renamed to strictly preserve Device Tree ABI backward compatibility.
>
> Signed-off-by: Yu-Chun Lin <eleanor.lin@realtek.com>

Thanks for working this out,
Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable