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

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Message-ID: <069e920c-7023-4a6d-b1c6-dc87ac9d2360@arm.com>
Date: Wed, 7 May 2025 09:52:02 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Yuanfang Zhang <quic_yuanfang@...cinc.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 07/05/2025 05:26, Yuanfang Zhang wrote:
> 
> 
> 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.

Thanks! Please could you make sure to describe all of this when sending
out a patch in the cover letter ?

Cheers
Suzuki


> 
> Yuanfang
> 
> 
> 
> 
> 
>