Re: [PATCH v2 2/4] dt-bindings: arm: Add binding document for Coresight Control Unit device.

[JieGan]

On Fri, Jul 05, 2024 at 11:07:22AM +0200, Krzysztof Kozlowski wrote:
> On 05/07/2024 11:00, Jie Gan wrote:
> > Add binding document for Coresight Control Unit device.
> 
> <form letter>
> Please use scripts/get_maintainers.pl to get a list of necessary people
> and lists to CC (and consider --no-git-fallback argument). It might
> happen, that command when run on an older kernel, gives you outdated
> entries. Therefore please be sure you base your patches on recent Linux
> kernel.
> 
> Tools like b4 or scripts/get_maintainer.pl provide you proper list of
> people, so fix your workflow. Tools might also fail if you work on some
> ancient tree (don't, instead use mainline) or work on fork of kernel
> (don't, instead use mainline). Just use b4 and everything should be
> fine, although remember about `b4 prep --auto-to-cc` if you added new
> patches to the patchset.
> </form letter>
> 
> Or stop developing on some old tree. It's some sort of weird pattern in
> entire Qualcomm Coresight - everything developed on old kernels.
> 
> You must work on latest mainline or maintainer or linux-next tree, not
> some old Qualcomm tree. Your v5.15, v5.19, v6.4 or v6.8 or whatever you
> have there: BIG NOPE.
> 
> > 
> > Signed-off-by: Jie Gan <quic_jiegan@xxxxxxxxxxx>
> > ---
> 
> Subject: it never ends with full stop.
> 
> A nit, subject: drop second/last, redundant "bindings". The
> "dt-bindings" prefix is already stating that these are bindings.
> See also:
> https://elixir.bootlin.com/linux/v6.7-rc8/source/Documentation/devicetree/bindings/submitting-patches.rst#L18
> 
> >  .../bindings/arm/qcom,coresight-ccu.yaml      | 87 +++++++++++++++++++
> >  1 file changed, 87 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-ccu.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-ccu.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-ccu.yaml
> > new file mode 100644
> > index 000000000000..9bb8ced393a7
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/qcom,coresight-ccu.yaml
> > @@ -0,0 +1,87 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/arm/qcom,coresight-ccu.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: CoreSight Control Unit
> > +
> > +maintainers:
> > +  - Yuanfang Zhang <quic_yuanfang@xxxxxxxxxxx>
> > +  - Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
> > +  - Jie Gan <quic_jiegan@xxxxxxxxxxx>
> > +
> > +description:
> > +  The Coresight Control unit controls various Coresight behaviors.
> > +  Used to enable/disable ETR’s data filter function based on trace ID.
> > +
> > +properties:
> > +  compatible:
> > +    const: qcom,coresight-ccu
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +
> > +  clock-names:
> > +    items:
> > +      - const: apb_pclk
> 
> Drop _pclk
Hi, Suzuki,
As Krzysztof proposed, we have to change the clock name from apb_pclk to apb.
According to the new clock name, I updated the inline function coresight_get_enable_apb_pclk
to vote the clock with the new name.

Is that ok with the change? Or any other suggestions?

static inline struct clk *coresight_get_enable_apb_pclk(struct device *dev)
{
        struct clk *pclk;
        int ret;

        pclk = clk_get(dev, "apb_pclk");
        if (IS_ERR(pclk)) {
                pclk = clk_get(dev, "apb");    //added line
                if (IS_ERR(pclk))
                        return NULL;
        }

        ret = clk_prepare_enable(pclk);
        if (ret) {
                clk_put(pclk);
                return ERR_PTR(ret);
        }
        return pclk;
}

> 
> > +
> > +  reg-names:
> 
> Please follow DTS coding style about order of properties.
> 
> > +    items:
> > +      - const: ccu-base
> > +
> > +  in-ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    unevaluatedProperties:
> 
> This was never tested and it cannot reliably work.
> 
> Sorry, this is waste of our time.
> 
> 
> > +      patternProperties:
> > +        '^port(@[0-7])?$':
> > +          description: Input connections from CoreSight Trace bus
> > +          $ref: /schemas/graph.yaml#/properties/port
> > +
> > +          properties:
> > +            qcom,ccu-atid-offset:
> > +              description:
> > +                Offset to the Coresight Control Unit component's ATID register
> > +                that is used by specific TMC ETR. The ATID register can be programed based
> > +                on the trace id to filter out specific trace data which gets into ETR buffer.
> > +              $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - in-ports
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    syscon@1001000 {
> 
> That's not a syscon.
> 
> > +        compatible = "qcom,coresight-ccu";
> > +        reg = <0x1001000 0x1000>;
> > +        reg-names = "ccu-base";
> > +
> 
> Best regards,
> Krzysztof
> 

Thanks,
Jie