The SpacemiT K1 SoC reuses the Marvell PXA910-compatible PWM controller
with one notable difference: the addition of a resets property. To make
the device tree pass schema validation (make dtbs_check W=3), this patch
updates the binding to accept spacemit,k1-pwm as a compatible string, when
used in conjunction with the fallback marvell,pxa910-pwm.

Support for the optional resets property is also added, as it is required
by the K1 integration but was not present in the original Marvell bindings.

Since the PWM reset line may be deasserted during the early bootloader
stage, making the resets property optional avoids potential
double-deassertion, which could otherwise cause flickering on displays
that use PWM for backlight control.

Signed-off-by: Guodong Xu <guodong@riscstar.com>
---
v2: Accept spacemit,k1-pwm as a compatible string, when used in conjunction
    with the fallback marvell,pxa910-pwm

.../bindings/pwm/marvell,pxa-pwm.yaml           | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml b/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml
index 9ee1946dc2e1..0d97333c7fee 100644
--- a/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml
+++ b/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml
@@ -14,11 +14,15 @@ allOf:
 
 properties:
   compatible:
-    enum:
-      - marvell,pxa250-pwm
-      - marvell,pxa270-pwm
-      - marvell,pxa168-pwm
-      - marvell,pxa910-pwm
+    oneOf:
+      - enum:
+          - marvell,pxa250-pwm
+          - marvell,pxa270-pwm
+          - marvell,pxa168-pwm
+          - marvell,pxa910-pwm
+      - items:
+          - const: spacemit,k1-pwm
+          - const: marvell,pxa910-pwm
 
   reg:
     # Length should be 0x10
@@ -31,6 +35,9 @@ properties:
   clocks:
     maxItems: 1
 
+  resets:
+    maxItems: 1
+
 required:
   - compatible
   - reg
-- 
2.43.0

On Sun, 20 Apr 2025 15:02:46 +0800, Guodong Xu wrote:
> The SpacemiT K1 SoC reuses the Marvell PXA910-compatible PWM controller
> with one notable difference: the addition of a resets property. To make
> the device tree pass schema validation (make dtbs_check W=3), this patch
> updates the binding to accept spacemit,k1-pwm as a compatible string, when
> used in conjunction with the fallback marvell,pxa910-pwm.
> 
> Support for the optional resets property is also added, as it is required
> by the K1 integration but was not present in the original Marvell bindings.
> 
> Since the PWM reset line may be deasserted during the early bootloader
> stage, making the resets property optional avoids potential
> double-deassertion, which could otherwise cause flickering on displays
> that use PWM for backlight control.
> 
> Signed-off-by: Guodong Xu <guodong@riscstar.com>
> ---
> v2: Accept spacemit,k1-pwm as a compatible string, when used in conjunction
>     with the fallback marvell,pxa910-pwm
> 
> .../bindings/pwm/marvell,pxa-pwm.yaml           | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>