Re: [PATCH 07/15] dt-bindings: clock: Add Ambarella clock bindings

[Li Chen <me@linux.beauty>]

Hi Krzysztof,

Sorry for my late reply.

On Mon, 23 Jan 2023 16:11:08 +0800,
Krzysztof Kozlowski wrote:
>
> On 23/01/2023 08:32, Li Chen wrote:
> > This patch introduce clock bindings for Ambarella.
> >
> > Signed-off-by: Li Chen <lchen@ambarella.com>
> > Change-Id: I29018a23ed3a5b79a1103e859a5c7ed7bb83a261
>
> All the same problems plus new:
>
> Subject: drop second/last, redundant "bindings". The "dt-bindings"
> prefix is already stating that these are bindings.

Well noted.

> > ---
> >  .../clock/ambarella,composite-clock.yaml      | 52 ++++++++++++++++
> >  .../bindings/clock/ambarella,pll-clock.yaml   | 59 +++++++++++++++++++
> >  MAINTAINERS                                   |  2 +
> >  3 files changed, 113 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/clock/ambarella,composite-clock.yaml
> >  create mode 100644 Documentation/devicetree/bindings/clock/ambarella,pll-clock.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/clock/ambarella,composite-clock.yaml b/Documentation/devicetree/bindings/clock/ambarella,composite-clock.yaml
> > new file mode 100644
> > index 000000000000..fac1cb9379c4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/ambarella,composite-clock.yaml
> > @@ -0,0 +1,52 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/clock/ambarella,composite-clock.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Ambarella Composite Clock
> > +
> > +maintainers:
> > +  - Li Chen <lchen@ambarella.com>
> > +
>
> Missing description.

Thanks, description as below will be added in v2:

"Ambarella SoCs integrates some composite clocks, like uart0, which aggrate the functionality
of the basic clock types, like mux and div."

> > +properties:
> > +  compatible:
> > +    items:
>
> Drop items.

Ok.

> > +      - const: ambarella,composite-clock
>
> Missing SoC specific compatible. This is anyway not really correct
> compatible...

Most Ambarella's compatibles don't contain SoC name, because we prefer
to use syscon + offsets in dts to tell driver the correct register offsets, or
ues struct soc_device and SoC identity stores in a given physical address.

So compatibles like "ambarella,composite-clock" and "ambarella,pinctrl" are
used widely in Ambarella kernels. Feel free to correct me if you think this
is not a good idea.

> > +
> > +  clocks: true
>
> No, needs constraints.

Ok. I will list all clocks name

> > +  assigned-clocks: true
> > +  assigned-clock-parents: true
> > +  assigned-clock-rates: true
>
> Drop these three.

Ok

> > +  clock-output-names: true
>
> Missing constraints.

Ok, I will add "maxItems: 1"

> > +  amb,mux-regmap: true
>
> NAK.
>
> It's enough. The patches have very, very poor quality.
>
> Missing description, missing type/$ref, wrong prefix.

Sorry, I forget to run dt_binding_check, I will spend some
time learning the binding and check, sorry for it.

> > +  amb,div-regmap: true
> > +  amb,div-width: true
> > +  amb,div-shift: true
>
> These two are arguments to phandle.

I will add description and $ref to regmap and width/shift.

> > +
> > +  '#clock-cells':
> > +    const: 0
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +  - '#clock-cells'
> > +
> > +additionalProperties: false
>
> So why you decided to add it here and not in other places?

I didn't understand it well. I will add it to other places in v2,
thanks for pointint out it.

> > +
> > +examples:
> > +  - |
> > +      gclk_uart0: gclk-uart0 {
>
> Wrong indentation.

Well noted.

> > +        #clock-cells = <0>;
> > +        compatible = "ambarella,composite-clock";
> > +        clocks = <&osc>, <&gclk_core>, <&pll_out_enet>, <&pll_out_sd>;
> > +        clock-output-names = "gclk_uart0";
> > +        assigned-clocks = <&gclk_uart0>;
> > +        assigned-clock-parents = <&osc>;
> > +        assigned-clock-rates = <24000000>;
> > +        amb,mux-regmap = <&rct_syscon 0x1c8>;
> > +        amb,div-regmap = <&rct_syscon 0x038>;
> > +        amb,div-width = <24>;
> > +        amb,div-shift = <0>;
> > +      };
> > diff --git a/Documentation/devicetree/bindings/clock/ambarella,pll-clock.yaml b/Documentation/devicetree/bindings/clock/ambarella,pll-clock.yaml
> > new file mode 100644
> > index 000000000000..65c1feb60041
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/ambarella,pll-clock.yaml
> > @@ -0,0 +1,59 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/clock/ambarella,pll-clock.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Ambarella PLL Clock
> > +
> > +maintainers:
> > +  - Li Chen <lchen@ambarella.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - ambarella,pll-clock
> > +      - ambarella,clkpll-v0
> > +
> > +if:
>
> No, this does not work like that. It sits under "allOf", located after
> "required:".

Thanks, I will learn "allOf" and use it in v2. BTW, we use the two compatibles as below:
clocks {
                compatible = "ambarella,clkpll-v0";
                ...
                gclk_core: gclk-core {
                        #clock-cells = <0>;
                        compatible = "ambarella,pll-clock";
                        clocks = <&osc>;
                        clock-output-names = "gclk_core";
                        amb,clk-regmap = <&rct_syscon 0x000 0x004 0x100 0x104 0x000 0x000>;
                };
                ...
}

I'm not sure can I describe the two compatibles in this single yaml, can you give some advice? thanks!

> > +  properties:
> > +    compatible:
> > +      const: ambarella,pll-clock
> > +
> > +then:
> > +  properties:
> > +    clocks:
> > +      maxItems: 1
> > +
> > +    clock-output-names: true
> > +    amb,clk-regmap: true
> > +    amb,frac-mode: true
> > +    assigned-clocks: true
> > +    assigned-clock-rates: true
>
> Same problems.

Ok.

> > +    gclk_axi: gclk-axi {
> > +        #clock-cells = <0>;
> > +        compatible = "fixed-factor-clock";
>
> What is this example about? Not related at all. Provide real example.

Sorry, I paste the wrong example, I will replace it with our gclk_core pll
instead.

Regards,
Li