linux-kernel - Re: [PATCH v10 4/7] Coresight: Introduce a new struct coresight

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Message-ID: <5e6edfce-ef2e-48d2-ad0c-0120606394fb@quicinc.com>
Date: Mon, 17 Feb 2025 09:14:51 +0800
From: Jie Gan <quic_jiegan@...cinc.com>
To: James Clark <james.clark@...aro.org>
CC: Tingwei Zhang <quic_tingweiz@...cinc.com>,
        Jinlong Mao
	<quic_jinlmao@...cinc.com>, <coresight@...ts.linaro.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        Suzuki K Poulose
	<suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        "Alexander
 Shishkin" <alexander.shishkin@...ux.intel.com>,
        Maxime Coquelin
	<mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Subject: Re: [PATCH v10 4/7] Coresight: Introduce a new struct coresight_path



On 2/14/2025 7:09 PM, James Clark wrote:
> 
> 
> On 14/02/2025 1:34 am, Jie Gan wrote:
>>
>>
>> On 2/14/2025 12:00 AM, James Clark wrote:
>>>
>>>
>>> On 07/02/2025 6:42 am, Jie Gan wrote:
>>>> Add 'struct coresight_path' to store the data that is needed by
>>>> coresight_enable_path/coresight_disable_path. The structure will be
>>>> transmitted to any required devices to enable related funcationalities.
>>>>
>>>> The trace_id will be allocated after the path is built. Consequently,
>>>> The ETM3x and ETM4x devices will directly read the trace_id from path
>>>> which result in etm_read_alloc_trace_id and etm4_read_alloc_trace_id
>>>> being deleted.
>>>>
>>>> Co-developed-by: James Clark <james.clark@...aro.org>
>>>> Signed-off-by: James Clark <james.clark@...aro.org>
>>>> Signed-off-by: Jie Gan <quic_jiegan@...cinc.com>
>>>> ---
>>>>   drivers/hwtracing/coresight/coresight-core.c  | 106 ++++++++++++ 
>>>> +-----
>>>>   drivers/hwtracing/coresight/coresight-dummy.c |   5 +-
>>>>   .../hwtracing/coresight/coresight-etm-perf.c  |  30 +++--
>>>>   .../hwtracing/coresight/coresight-etm-perf.h  |   2 +-
>>>>   drivers/hwtracing/coresight/coresight-etm.h   |   1 -
>>>>   .../coresight/coresight-etm3x-core.c          |  54 ++-------
>>>>   .../coresight/coresight-etm4x-core.c          |  54 ++-------
>>>>   drivers/hwtracing/coresight/coresight-etm4x.h |   1 -
>>>>   drivers/hwtracing/coresight/coresight-priv.h  |  12 +-
>>>>   drivers/hwtracing/coresight/coresight-stm.c   |   3 +-
>>>>   drivers/hwtracing/coresight/coresight-sysfs.c |  17 ++-
>>>>   drivers/hwtracing/coresight/coresight-tpdm.c  |   3 +-
>>>>   include/linux/coresight.h                     |  12 +-
>>>>   13 files changed, 143 insertions(+), 157 deletions(-)
>>>>
>>> [...]
>>>> @@ -352,7 +352,7 @@ static void *etm_setup_aux(struct perf_event 
>>>> *event, void **pages,
>>>>        * CPUs, we can handle it and fail the session.
>>>>        */
>>>>       for_each_cpu(cpu, mask) {
>>>> -        struct list_head *path;
>>>> +        struct coresight_path *path;
>>>>           struct coresight_device *csdev;
>>>>           csdev = per_cpu(csdev_src, cpu);
>>>> @@ -405,15 +405,15 @@ static void *etm_setup_aux(struct perf_event 
>>>> *event, void **pages,
>>>>               cpumask_clear_cpu(cpu, mask);
>>>>               continue;
>>>>           }
>>>> -
>>>>           /* ensure we can allocate a trace ID for this CPU */
>>>> -        trace_id = coresight_trace_id_get_cpu_id_map(cpu, &sink- 
>>>> >perf_sink_id_map);
>>>> -        if (!IS_VALID_CS_TRACE_ID(trace_id)) {
>>>> +        trace_id = coresight_path_assign_trace_id(path, CS_MODE_PERF);
>>>> +
>>>> +        /* Can be 0 and valid, ETE doesn't need an ID */
>>>> +        if (trace_id < 0) {
>>>
>>> Not sure why I wrote it like this, but I think we should leave it as 
>>> it was with !IS_VALID_CS_TRACE_ID(). Even with ETE it calls the trace 
>>> ID allocator, so nothing has changed here.
>>>
>> Sure, Will restore. For ETE or ETM, we dont need traverse the path, 
>> just directly allocate the trace id based on cpu id.
>>
>> Jie
>>
>>
> 
> Sorry I meant to only keep the !IS_VALID_CS_TRACE_ID() bit. We still 
> need to call the new coresight_path_assign_trace_id() otherwise it 
> doesn't get assigned to the path. I saw that got removed in v11.
> 
> 
Sorry for the misunderstanding, I was focused on "nothing has changed 
here", lol.

I got your point here.
So the updated codes should be:
...
                 /* ensure we can allocate a trace ID for this CPU */
                 trace_id = coresight_path_assign_trace_id(path, 
CS_MODE_PERF);
                 if (!IS_VALID_CS_TRACE_ID(trace_id)) {
                         cpumask_clear_cpu(cpu, mask);
                         coresight_release_path(path);
                         continue;
                 }
...


Thanks,
Jie