Hello Uwe,
Am Montag, 6. November 2023, 11:36:21 CET schrieb Uwe Kleine-König:
> Hello,
>
> [dropped Philippe Schenker from Cc as his email bounced in the past]
>
> On Mon, Nov 06, 2023 at 10:52:03AM +0100, Alexander Stein wrote:
> > Only fsl,imx1-pwm comptabile devices use #pwm-cells = <2>. Newer SoCs
> > supportinverted PWM output, thus #pwm-cells needs to be set to 3.
> >
> > Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > ---
> >
> > .../devicetree/bindings/pwm/imx-pwm.yaml | 20 ++++++++++++++++---
> > 1 file changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.yaml
> > b/Documentation/devicetree/bindings/pwm/imx-pwm.yaml index
> > c01dff3b7f843..59a981c0f39ab 100644
> > --- a/Documentation/devicetree/bindings/pwm/imx-pwm.yaml
> > +++ b/Documentation/devicetree/bindings/pwm/imx-pwm.yaml
> > @@ -9,9 +9,6 @@ title: Freescale i.MX PWM controller
> >
> > maintainers:
> > - Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> >
> > -allOf:
> > - - $ref: pwm.yaml#
> > -
> >
> > properties:
> > "#pwm-cells":
> > description: |
> >
> > @@ -74,6 +71,23 @@ required:
> > additionalProperties: false
> >
> > +allOf:
> > + - $ref: pwm.yaml#
> > +
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: fsl,imx1-pwm
> > + then:
> > + properties:
> > + "#pwm-cells":
> > + enum: [2]
>
> Given that arch/arm/boot/dts/nxp/imx/imx1.dtsi has:
>
> pwm: pwm@208000 {
> #pwm-cells = <3>;
> compatible = "fsl,imx1-pwm";
> ...
>
> this looks wrong.
Indeed, something i doesn't match. Checking with [1] section 22.4.1 there are
no bits regarding output inversion. Also pwm_imx1_apply returns -EINVAL if
state->polarity != PWM_POLARITY_NORMAL.
So IMO "#pwm-cells = <3>" is wrong for imx1. If fixed to 2, this also matches
the description for the value of #pwm-cells in imx-pwm.yaml.
Best regards,
Alexander
[1] https://www.nxp.com/docs/en/reference-manual/MC9328MX1RM.pdf
>
> Best regards
> Uwe
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