Re: [PATCH v2 2/3] dt-bindings: arm: Add Coresight Dummy Trace YAML schema

From: Mike Leach
Date: Tue Mar 28 2023 - 06:13:21 EST


Hi,

As per my comments in the previous patch in this set....

On Mon, 27 Mar 2023 at 08:38, Hao Zhang <quic_hazha@xxxxxxxxxxx> wrote:
>
> Hi Krzysztof,
>
> On 3/25/2023 7:49 PM, Krzysztof Kozlowski wrote:
> > On 24/03/2023 07:16, Hao Zhang wrote:
> >> Add new coresight-dummy.yaml file describing the bindings required
> >> to define coresight dummy trace in the device trees.
> >>
> >
> > Subject: drop second/last, redundant "YAML schema". The "dt-bindings"
> > prefix is already stating that these are bindings and all new must be DT
> > schema. You cannot add anything else, so this is redundant.
> >
> I will take your advice to drop redundant part of title in the next
> version of patch.
> >
> >> Signed-off-by: Hao Zhang <quic_hazha@xxxxxxxxxxx>
> >> ---
> >> .../bindings/arm/qcom,coresight-dummy.yaml | 118 ++++++++++++++++++
> >> 1 file changed, 118 insertions(+)
> >> create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
> >> new file mode 100644
> >> index 000000000000..7b719b084d72
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
> >> @@ -0,0 +1,118 @@
> >> +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
> >> +# Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/arm/qcom,coresight-dummy.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: QCOM Coresight Dummy component
> >> +
> >> +description: |
> >> + The Coresight Dummy component is for the specific devices that HLOS don't have
> >> + permission to access or configure. Such as Coresight sink EUD, some TPDMs etc.
> >> + So there need driver to register dummy devices as Coresight devices. Provide
> >> + Coresight API for dummy device operations, such as enabling and disabling
> >> + dummy devices. Build the Coresight path for dummy sink or dummy source for
> >> + debugging.
> >> +
> >> + The primary use case of the coresight dummy is to build path for dummy sink or
> >> + dummy source.
> >> +
> >> +maintainers:
> >> + - Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
> >> + - Tao Zhang <quic_taozha@xxxxxxxxxxx>
> >> + - Hao Zhang <quic_hazha@xxxxxxxxxxx>
> >> +
> >> +select:
> >> + properties:
> >> + compatible:
> >> + contains:
> >> + enum:
> >> + - qcom,coresight-dummy

Can we have coresight-dummy-source and coresight-dummy-sink?

> >> + required:
> >> + - compatible
> >
> > Why do you need the select?
> >
> This is a mistake, will remove it in the next version of patch.
> >> +
> >> +properties:
> >> + $nodename:
> >> + pattern: "^dummy_.*(sink|source)_[0-9]+.*$"
> >
> > We do not enforce node names in individual bindings. Why do you need it?
> > Plus underscore is not even proper character...
> >
> I will remove this node.
>
> >> + compatible:
> >> + items:
> >
> > Drop items. You have only one item, so no need for list.
>
> I will take your advice and update it in the next version of patch.
>
> >> + - const: qcom,coresight-dummy
> >> +
> >> + qcom,dummy-sink:
> >> + type: boolean
> >> + description:
> >> + Indicates that the type of this coresight node is dummy sink.
> >
> > You just duplicated property name. Write something useful.
> >
> >> +
> >> + qcom,dummy-source:
> >> + type: boolean
> >> + description:
> >> + Indicates that the type of this coresight node is dummy source.
> >
> > You just duplicated property name. Write something useful.
> >
>

These properties not required if the compatible name is more specific

> Sure, I will add more details for it.
>
> >> +
> >> + out-ports:
> >> + description: |
> >
> > No need for |
> >
> >> + Output connections from the dummy source to Coresight Trace bus.
> >> + $ref: /schemas/graph.yaml#/properties/ports
> >> +
> >> + properties:
> >> + port:
> >> + description: Output connection from the dummy source to Coresight
> >> + Trace bus.
> >> + $ref: /schemas/graph.yaml#/properties/port
> >> +
> >> + in-ports:
> >> + description: |
> >
> > Ditto
> >
> I will remove it in the next version of patch.
>
> >> + Input connections from the CoreSight Trace bus to dummy sink.
> >> + $ref: /schemas/graph.yaml#/properties/ports
> >> +
> >> + properties:
> >> + port:
> >> + description: Input connection from the Coresight Trace bus to
> >> + dummy sink.
> >> + $ref: /schemas/graph.yaml#/properties/port
> >> +
> >> +required:
> >> + - compatible
> >> +

The binding should constrain out ports to dummy-source only, and in
ports to dummy sink only.

Regards

Mike

> >> +additionalProperties: false
> >> +
> >> +oneOf:
> >> + - required:
> >> + - qcom,dummy-sink
> >> + - required:
> >> + - qcom,dummy-source
> >> +
> >> +examples:
> >> + # minimum dummy sink definition. dummy sink connect to coresight replicator.
> >> + - |
> >> + dummy_sink_1 {
> >
> > Node names should be generic, so "sink"
> > https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> >
> >> + compatible = "qcom,coresight-dummy";
> >> + qcom,dummy-sink;
> >> +
> >> + in-ports {
> >> + port {
> >> + eud_in_replicator_swao: endpoint {
> >> + remote-endpoint =
> >> + <&replicator_swao_out_eud>;
> >
> > Why line break after =?
> >
>
> >> + };
> >> + };
> >> + };
> >> + };
> >> +
> >> + # minimum dummy source definition. dummy source connect to coresight funnel.
> >
> > If you use sentences, then start with capital letter.
> >
>
> I will update it according to your advice in the next version of patch.
>
> >> + - |
> >> + dummy_source_1 {
> >> + compatible = "qcom,coresight-dummy";
> >> + qcom,dummy-source;
> >> +
> >> + out-ports {
> >> + port {
> >> + dummy_riscv_out_funnel_swao: endpoint {
> >> + remote-endpoint =
> >> + <&funnel_swao_in_dummy_riscv>;
> >
> > Why line break?
>
> I copy it from device tree and keep the original format, will correct
> the format in the next version of patch.
>
> Thanks,
> Hao
>
> >> + };
> >> + };
> >> + };
> >> + };
> >> +
> >> +...
> >
> > Best regards,
> > Krzysztof
> >



--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK