linux-kernel - Re: [PATCH v3 2/6] coresight: Introduce pause and resume APIs for source

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Message-ID: <CAJ9a7VjcWHiRQmWW3sWTf8iBWMr5K3zCCJ6RF=i6bU+qO154qA@mail.gmail.com>
Date: Tue, 1 Apr 2025 11:01:49 +0100
From: Mike Leach <mike.leach@...aro.org>
To: Leo Yan <leo.yan@....com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>, James Clark <james.clark@...aro.org>, 
	Jonathan Corbet <corbet@....net>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
	coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/6] coresight: Introduce pause and resume APIs for source

On Tue, 11 Mar 2025 at 17:05, Leo Yan <leo.yan@....com> wrote:
>
> Introduce APIs for pausing and resuming trace source and export as GPL
> symbols.
>
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
>  drivers/hwtracing/coresight/coresight-core.c | 22 ++++++++++++++++++++
>  drivers/hwtracing/coresight/coresight-priv.h |  2 ++
>  include/linux/coresight.h                    |  4 ++++
>  3 files changed, 28 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index fb43ef6a3b1f..d4c3000608f2 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -367,6 +367,28 @@ void coresight_disable_source(struct coresight_device *csdev, void *data)
>  }
>  EXPORT_SYMBOL_GPL(coresight_disable_source);
>
> +void coresight_pause_source(struct coresight_device *csdev)
> +{
> +       if (!coresight_is_percpu_source(csdev))
> +               return;
> +
> +       if (source_ops(csdev)->pause_perf)
> +               source_ops(csdev)->pause_perf(csdev);
> +}
> +EXPORT_SYMBOL_GPL(coresight_pause_source);
> +
> +int coresight_resume_source(struct coresight_device *csdev)
> +{
> +       if (!coresight_is_percpu_source(csdev))
> +               return -EOPNOTSUPP;
> +
> +       if (!source_ops(csdev)->resume_perf)
> +               return -EOPNOTSUPP;
> +
> +       return source_ops(csdev)->resume_perf(csdev);
> +}
> +EXPORT_SYMBOL_GPL(coresight_resume_source);
> +
>  /*
>   * coresight_disable_path_from : Disable components in the given path beyond
>   * @nd in the list. If @nd is NULL, all the components, except the SOURCE are
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index 82644aff8d2b..2d9baa9d8228 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -249,5 +249,7 @@ void coresight_add_helper(struct coresight_device *csdev,
>  void coresight_set_percpu_sink(int cpu, struct coresight_device *csdev);
>  struct coresight_device *coresight_get_percpu_sink(int cpu);
>  void coresight_disable_source(struct coresight_device *csdev, void *data);
> +void coresight_pause_source(struct coresight_device *csdev);
> +int coresight_resume_source(struct coresight_device *csdev);
>
>  #endif
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index d79a242b271d..c95c72e07e02 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -398,6 +398,8 @@ struct coresight_ops_link {
>   *             is associated to.
>   * @enable:    enables tracing for a source.
>   * @disable:   disables tracing for a source.
> + * @resume_perf: resumes tracing for a source in perf session.
> + * @pause_perf:        pauses tracing for a source in perf session.
>   */
>  struct coresight_ops_source {
>         int (*cpu_id)(struct coresight_device *csdev);
> @@ -405,6 +407,8 @@ struct coresight_ops_source {
>                       enum cs_mode mode, struct coresight_path *path);
>         void (*disable)(struct coresight_device *csdev,
>                         struct perf_event *event);
> +       int (*resume_perf)(struct coresight_device *csdev);
> +       void (*pause_perf)(struct coresight_device *csdev);
>  };
>
>  /**
> --
> 2.34.1
>

Reviewed-by: Mike Leach <mike.leach@...aro.org>
-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK