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

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Message-ID: <a633f52c-81e8-4c0d-aca7-cc18360866eb@linaro.org>
Date: Thu, 13 Feb 2025 16:00:04 +0000
From: James Clark <james.clark@...aro.org>
To: Jie Gan <quic_jiegan@...cinc.com>
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 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.