Re: [PATCH v2 1/9] dt-bindings: arm: Add support for DSB element

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 27/02/2023 03:07, Tao Zhang wrote:
> Hi Suzuki,
> 
> 在 2/22/2023 2:11 AM, Suzuki K Poulose 写道:
>> On 19/01/2023 07:41, Tao Zhang wrote:
>>> Add property "qcom,dsb-elem-size" to support DSB(Discrete Single
>>> Bit) element for TPDA. Specifies the DSB element size supported
>>> by each monitor connected to the aggregator on each port. Should
>>> be specified in pairs (port, dsb element size).
>>>
>>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
>>> Signed-off-by: Tao Zhang <taozha@qti.qualcomm.com>
>>> ---
>>>   .../bindings/arm/qcom,coresight-tpda.yaml          | 22 
>>> ++++++++++++++++++++++
>>>   1 file changed, 22 insertions(+)
>>>
>>> diff --git 
>>> a/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml 
>>> b/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml
>>> index 2ec9b5b..298db7f 100644
>>> --- a/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml
>>> +++ b/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml
>>> @@ -58,6 +58,26 @@ properties:
>>>       minItems: 1
>>>       maxItems: 2
>>>   +  qcom,dsb-element-size:
>>> +    description: |
>>> +      Specifies the DSB(Discrete Single Bit) element size supported by
>>> +      each monitor connected to the aggregator on each port. Should be
>>> +      specified in pairs <port, dsb element size>.
>>
>> Isn't this a property of the TPDM connected to the port ? i.e. the DSB 
>> size ? Thus shouldn't this be part of the TPDM device (and the TPDA 
>> will be able to find it from the TPDM device) ?
>>
> Since  the port number is about the input port of TPDA, this property 
> needs to be configured in the TPDA-related settings.

That is because, you chose to describe the property of TPDM in TPDA ?
Instead if you do it as follows :

  tpdm {
        qcom,tpdm-dsb-elemenet-size = <32>
        out_ports {

	port {
              remote-endpoint=<&tpda_port_number>;
	}
  }

  tpda {
        in_ports {
            port {
                  remote-endpoint=<&tpdm0_port0>;
            }
        }
  }


The TPDA driver can figure out the "port" that a given TPDM is connected
to and thus find out the DSB size. For the tpda driver, pdata->conns
could hold the reference to the TPDM device and thus fetch the DSB size.
(Note: James is working on a patch to add input port connections to the
platform data).

Suzuki