[PATCH v2 0/2] watchdog: realtek-otto: add fallback compatible

[PATCH v2 0/2] watchdog: realtek-otto: add fallback compatible

[Sander Vanheule]

Like for the GPIO hardware of the Realtek Otto platform, add a fallback
compatible for the watchdog hardware.

For backward compatibility, the binding will still allow current
single-compatible devicetrees to work, but new devicetrees, including
new compatibles, should use a two-component compatible.

This series serves to address comments regarding the device compatibles
for the patches adding RTL9607C watchdog support [1].

[1] https://lore.kernel.org/lkml/20260509163101.722793-1-adilov@disroot.org/

Sander Vanheule (2):
  dt-bindings: watchdog: realtek,otto-wdt: Add fallback compatible
  watchdog: realtek-otto: add fallback compatible

 .../bindings/watchdog/realtek,otto-wdt.yaml   | 22 ++++++++++++++-----
 drivers/watchdog/realtek_otto_wdt.c           |  2 ++
 2 files changed, 18 insertions(+), 6 deletions(-)

-- 
2.54.0

[PATCH v2 1/2] dt-bindings: watchdog: realtek,otto-wdt: Add fallback compatible

[Sander Vanheule]

As all known hardware instantiations of this watchdog behave the same, a
fallback compatible can be added.

To remain compatible with existing single-compatible bindings, the
current compatibles are duplicated. New compatibles should only be added
to the list with fallback.

Signed-off-by: Sander Vanheule <sander@svanheule.net>
---
Changes since v1:
- Fix indendations
- Add deprecated property to old compatible
- Use two-part compatible in example
---
 .../bindings/watchdog/realtek,otto-wdt.yaml   | 22 ++++++++++++++-----
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml b/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
index 1f5390a67cdb..e470e0fcbb2a 100644
--- a/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
+++ b/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
@@ -25,11 +25,21 @@ allOf:
 
 properties:
   compatible:
-    enum:
-      - realtek,rtl8380-wdt
-      - realtek,rtl8390-wdt
-      - realtek,rtl9300-wdt
-      - realtek,rtl9310-wdt
+    oneOf:
+      - items:
+          - enum:
+              - realtek,rtl8380-wdt
+              - realtek,rtl8390-wdt
+              - realtek,rtl9300-wdt
+              - realtek,rtl9310-wdt
+          - const: realtek,otto-wdt
+      # Legacy without fallback, do not extend
+      - deprecated: true
+        enum:
+          - realtek,rtl8380-wdt
+          - realtek,rtl8390-wdt
+          - realtek,rtl9300-wdt
+          - realtek,rtl9310-wdt
 
   reg:
     maxItems: 1
@@ -74,7 +84,7 @@ unevaluatedProperties: false
 examples:
   - |
     watchdog: watchdog@3150 {
-        compatible = "realtek,rtl8380-wdt";
+        compatible = "realtek,rtl8380-wdt", "realtek,otto-wdt";
         reg = <0x3150 0xc>;
 
         realtek,reset-mode = "soc";
-- 
2.54.0

Re: [PATCH v2 1/2] dt-bindings: watchdog: realtek,otto-wdt: Add fallback compatible

[Guenter Roeck]

On Tue, May 12, 2026 at 10:48:53PM +0200, Sander Vanheule wrote:
> As all known hardware instantiations of this watchdog behave the same, a
> fallback compatible can be added.
> 
> To remain compatible with existing single-compatible bindings, the
> current compatibles are duplicated. New compatibles should only be added
> to the list with fallback.
> 
> Signed-off-by: Sander Vanheule <sander@svanheule.net>
> ---
> Changes since v1:
> - Fix indendations
> - Add deprecated property to old compatible
> - Use two-part compatible in example
> ---
>  .../bindings/watchdog/realtek,otto-wdt.yaml   | 22 ++++++++++++++-----
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml b/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
> index 1f5390a67cdb..e470e0fcbb2a 100644
> --- a/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
> +++ b/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
> @@ -25,11 +25,21 @@ allOf:
>  
>  properties:
>    compatible:
> -    enum:
> -      - realtek,rtl8380-wdt
> -      - realtek,rtl8390-wdt
> -      - realtek,rtl9300-wdt
> -      - realtek,rtl9310-wdt
> +    oneOf:
> +      - items:
> +          - enum:
> +              - realtek,rtl8380-wdt
> +              - realtek,rtl8390-wdt
> +              - realtek,rtl9300-wdt
> +              - realtek,rtl9310-wdt
> +          - const: realtek,otto-wdt

For the Apple watchdog driver, the generic property "apple,wdt" is
considered to be bad and is not supposed to be used for newer chips.
For this watchdog driver, a generic property is introduced.

What is the overall logic ? Is there some rule when a generic property
such as "realtek,otto-wdt" is appropriate and preferred, and when it isn't
(as in "apple,wdt") ?

Thanks,
Guenter

[PATCH v2 2/2] watchdog: realtek-otto: add fallback compatible

[Sander Vanheule]

As the binding now supports a fallback compatible for (new) devicetrees,
let's add it to the list of supported compatibles. If new compatibles
are added to the binding, driver updates may no longer be required.

Signed-off-by: Sander Vanheule <sander@svanheule.net>
---
 drivers/watchdog/realtek_otto_wdt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/watchdog/realtek_otto_wdt.c b/drivers/watchdog/realtek_otto_wdt.c
index 2c30ddd574c5..b4eb2f87f991 100644
--- a/drivers/watchdog/realtek_otto_wdt.c
+++ b/drivers/watchdog/realtek_otto_wdt.c
@@ -350,6 +350,8 @@ static int otto_wdt_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id otto_wdt_ids[] = {
+	{ .compatible = "realtek,otto-wdt" },
+	/* Legacy bindings without fallback compatible */
 	{ .compatible = "realtek,rtl8380-wdt" },
 	{ .compatible = "realtek,rtl8390-wdt" },
 	{ .compatible = "realtek,rtl9300-wdt" },
-- 
2.54.0