Re: Re: [PATCH v4 1/2] dt-bindings: pwm: dwc: add reset optional

Conor Dooley
2026-04-16T15:29:35Z

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On Thu, Apr 16, 2026 at 05:38:59PM +0800, Xuyang Dong wrote:
> > > >
> > > > The DesignWare PWM includes separate reset signals dedicated to each clock
> > > > domain:
> > > > The presetn signal resets logic in pclk domain.
> > > > The timer_N_resetn signal resets logic in the timer_N_clk domain.
> > > > The resets are active-low.
> > > >
> > > > Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>
> > >
> > > This commit implies that your hardware differs from existing devices,
> > > I think you should add a device-specific compatible.
> > >
>
> Hi Conor and Krzysztof,
>
> The DesignWare PWM Databook for 2.13a says: "The DW_apb_timers includes
> separate reset signals dedicated to each clock domain". They are:
> The presetn signal resets logic in pclk domain (i.e., the bus clock in DT).
> The timer_N_resetn signal resets logic in the timer_N_clk domain (i.e.,
> the timer clock in DT).
>
> These reset signals are optional; it is up to the designer's
> implementation.

Right, and it's that "designer's implementation" that warrants a
device-specific compatible.

>
> According to [1], the applied YAML is also based on 2.13a, so our
> hardware is the same as the existing devices. It's just that these two
> reset signals were missing from the original YAML binding.
>
> [1] https://lore.kernel.org/linux-pwm/8bb5103d-803e-90d2-fd93-132bb2aac2d6@sifive.com/
>
> > > > ---
> > > > .../devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml | 3 +++
> > > > 1 file changed, 3 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml b/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
> > > > index 7523a89a1773..a8bbad0360f8 100644
> > > > --- a/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
> > > > +++ b/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
> > > > @@ -43,6 +43,9 @@ properties:
> > > > - const: bus
> > > > - const: timer
> > > >
> > > > + resets:
> > > > + maxItems: 2
> >
> > And this should really be listed with description, because order is
> > fixed.
> >
>
> The description of resets will be listed in next version.
>
> Best regards,
> Xuyang Dong

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