linux-kernel - Re: [PATCH v3 2/2] coresight: add coresight Trace Network On Chip driver

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Message-ID: <4a6a8bad-e5d9-4613-a839-5a21491ef7c4@quicinc.com>
Date: Wed, 7 May 2025 12:26:10 +0800
From: Yuanfang Zhang <quic_yuanfang@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach
	<mike.leach@...aro.org>,
        James Clark <james.clark@...aro.org>, Rob Herring
	<robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Alexander Shishkin
	<alexander.shishkin@...ux.intel.com>
CC: <kernel@....qualcomm.com>, <linux-arm-msm@...r.kernel.org>,
        <coresight@...ts.linaro.org>, <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] coresight: add coresight Trace Network On Chip
 driver



On 5/6/2025 7:20 PM, Suzuki K Poulose wrote:
> On 14/04/2025 10:16, Yuanfang Zhang wrote:
>>
>>
>> On 4/11/2025 5:59 PM, Suzuki K Poulose wrote:
>>> On 11/04/2025 09:57, Yuanfang Zhang wrote:
>>>> Add a driver to support Coresight device Trace Network On Chip (TNOC),
>>>> which is an integration hierarchy integrating functionalities of TPDA
>>>> and funnels. It aggregates the trace and transports to coresight trace
>>>> bus.
>>>>
>>>> Compared to current configuration, it has the following advantages:
>>>> 1. Reduce wires between subsystems.
>>>> 2. Continue cleaning the infrastructure.
>>>> 3. Reduce Data overhead by transporting raw data from source to target.
>>>>
>>>>     +------------------------+                +-------------------------+
>>>>     | Video Subsystem        |                |Video Subsystem          |
>>>>     |       +-------------+  |                |       +------------+    |
>>>>     |       | Video TPDM  |  |                |       | Video TPDM |    |
>>>>     |       +-------------+  |                |       +------------+    |
>>>>     |            |           |                |              |          |
>>>>     |            v           |                |              v          |
>>>>     |   +---------------+    |                |        +-----------+    |
>>>>     |   | Video funnel  |    |                |        |Video TNOC |    |
>>>>     |   +---------------+    |                |        +-----------+    |
>>>>     +------------|-----------+                +------------|------------+
>>>>                  |                                         |
>>>>                  v-----+                                   |
>>>> +--------------------|---------+                         |
>>>> |  Multimedia        v         |                         |
>>>> |  Subsystem   +--------+      |                         |
>>>> |              |  TPDA  |      |                         v
>>>> |              +----|---+      |              +---------------------+
>>>> |                   |          |              |    Aggregator TNOC  |
>>>> |                   |          |              +----------|----------+
>>>> |                   +--        |                         |
>>>> |                     |        |                         |
>>>> |                     |        |                         |
>>>> |              +------v-----+  |                         |
>>>> |              |  Funnel    |  |                         |
>>>> |              +------------+  |                         |
>>>> +----------------|-------------+                         |
>>>>                    |                                       |
>>>>                    v                                       v
>>>>         +--------------------+                    +------------------+
>>>>         |   Coresight Sink   |                    |  Coresight Sink  |
>>>>         +--------------------+                    +------------------+
>>>
>>> If each NOC has TraceID, how do you reliably decode the trace ?
>>> Is there a single NOC/TPDA in the path from Source to sink ?
>>
>> Not each TNOC has TraceID, there is only one TNOC has TraceID for one path
>> from Source to sink. In the example, only the aggregator TNOC has traceID.
>> Decode trace relying on TraceID + Inport number.
>> It can has mutiple TNOC/TPDA in one path.
> 
> So do we only describe the TNOCs that need traceId in the DT ? (e.g., Aggregator TNOC above ?) How about Video TNOC ? Don't we allocate a
> trace id for it by default, when it is described ?
> 
> Suzuki
> 
yes, now only describe the TNOCs which need traceID, Video TNOC is another type, it is interconnect TNOC which collects trace from subsystems
and transfers Aggr TNOC, it doesn't have ATID. Its driver is different from this patch, I want to describe it when upstream its driver.

Yuanfang