Re: [PATCH v3 2/4] dt-bindings: arm: mediatek: Add new bindings of MediaTek frequency hopping

[AngeloGioacchino Del Regno]

Il 06/10/22 13:23, Johnson Wang (王聖鑫) ha scritto:
> On Fri, 2022-09-30 at 14:07 -0500, Rob Herring wrote:
> > On Thu, Sep 29, 2022 at 03:07:49PM +0200, AngeloGioacchino Del Regno
> > wrote:
> > > Il 29/09/22 13:46, Johnson Wang ha scritto:
> > > > Add the new binding documentation for MediaTek frequency hopping
> > > > and spread spectrum clocking control.
> > > >
> > > > Co-developed-by: Edward-JW Yang <edward-jw.yang@xxxxxxxxxxxx>
> > > > Signed-off-by: Edward-JW Yang <edward-jw.yang@xxxxxxxxxxxx>
> > > > Signed-off-by: Johnson Wang <johnson.wang@xxxxxxxxxxxx>
> > > > ---
> > > >    .../arm/mediatek/mediatek,mt8186-fhctl.yaml   | 53
> > > > +++++++++++++++++++
> > > >    1 file changed, 53 insertions(+)
> > > >    create mode 100644
> > > > Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-
> > > > fhctl.yaml
> > > >
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-
> > > > fhctl.yaml
> > > > b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-
> > > > fhctl.yaml
> > > > new file mode 100644
> > > > index 000000000000..258dff7ce6bc
> > > > --- /dev/null
> > > > +++
> > > > b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-
> > > > fhctl.yaml
> > > > @@ -0,0 +1,53 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id:
> > > > https://urldefense.com/v3/__http://devicetree.org/schemas/arm/mediatek/mediatek,mt8186-fhctl.yaml*__;Iw!!CTRNKA9wMg0ARbw!xVt73f8PaQKph8n0ffGHHmQIxdzooUtGr0xDNVqy_6V0vwcs5k-FLrmkB3PZupSu1ciC$
> > > >   
> > > > +$schema:
> > > > https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!xVt73f8PaQKph8n0ffGHHmQIxdzooUtGr0xDNVqy_6V0vwcs5k-FLrmkB3PZulXwBACk$
> > > >   
> > > > +
> > > > +title: MediaTek frequency hopping and spread spectrum clocking
> > > > control
> > > > +
> > > > +maintainers:
> > > > +  - Edward-JW Yang <edward-jw.yang@xxxxxxxxxxxx>
> > > > +
> > > > +description: |
> > > > +  Frequency hopping control (FHCTL) is a piece of hardware that
> > > > control
> > > > +  some PLLs to adopt "hopping" mechanism to adjust their
> > > > frequency.
> > > > +  Spread spectrum clocking (SSC) is another function provided by
> > > > this hardware.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: mediatek,mt8186-fhctl
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +  clocks:
> > > > +    description: Phandles of the PLL with FHCTL hardware
> > > > capability.
> > > > +    minItems: 1
> > > > +    maxItems: 30
> > > > +
> > > > +  mediatek,hopping-ssc-percent:
> > > > +    description: The percentage of spread spectrum clocking for
> > > > one PLL.
> > > > +    minItems: 1
> > > > +    maxItems: 30
> > > > +    items:
> > > > +      default: 0
> > > > +      minimum: 0
> > > > +      maximum: 8
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +  - clocks
> > > > +
> > > > +additionalProperties: false
> > > > +
> > > > +examples:
> > > > +  - |
> > > > +    #include <dt-bindings/clock/mt8186-clk.h>
> > > > +    fhctl: fhctl@1000ce00 {
> > > > +        compatible = "mediatek,mt8186-fhctl";
> > > > +        reg = <0x1000c000 0xe00>;
> > > > +        clocks = <&apmixedsys CLK_APMIXED_MSDCPLL>;
> > > > +        mediatek,hopping-ssc-percent = <3>;
> > > > +    };
> > >
> > >
> > > .... a more realistic example:
> >
> > One or 2 cells is really outside the scope of the binding as either
> > is
> > valid. If the parent bus only has 32-bits of address space, there's
> > little reason to use 2 cells.
>
> Hi Rob,
>
> Thanks for the explanation.
>
> Then I will keep this example the same in the next version.

That was just to have it 1:1 with how it'll be written in the devicetree....
....in any case, Johnson, there's a discrepancy in the iospace:
1000ce00 vs 0c1000c000 - that has to be fixed anyway.

Cheers,
Angelo

> BRs,
> Johnson Wang
> > >      #include <dt-bindings/clock/mt8186-clk.h>
> > >
> > >      soc {
> > >          #address-cells = <2>;
> > >          #size-cells = <2>;
> > >
> > >          fhctl: fhctl@1000ce00 {
> > >              compatible = "mediatek,mt8186-fhctl";
> > >              reg = <0 0x1000c000 0 0xe00>;
> > >              clocks = <&apmixedsys CLK_APMIXED_MSDCPLL>;
> > >              mediatek,hopping-ssc-percent = <3>;
> > >          };
> > >      };
> > >
> > > After which...
> > >
> > > Reviewed-by: AngeloGioacchino Del Regno <
> > > angelogioacchino.delregno@xxxxxxxxxxxxx>