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From:   Mike Leach <mike.leach@linaro.org>
Date:   Tue, 17 Jan 2023 13:02:29 +0000
Message-ID: <CAJ9a7VixL9f2Cm7A780V311KH2G2giryeH9dG0p2e4zWBwA3iQ@mail.gmail.com>
Subject: Re: [PATCH v7 01/15] coresight: trace-id: Add API to dynamically
 assign Trace ID values
To:     Suzuki K Poulose <suzuki.poulose@arm.com>
Cc:     coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, mathieu.poirier@linaro.org,
        peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
        linux-perf-users@vger.kernel.org, leo.yan@linaro.org,
        quic_jinlmao@quicinc.com
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On Mon, 16 Jan 2023 at 14:16, Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
> Hi Mike
>
> On 16/01/2023 12:49, Mike Leach wrote:
> > The existing mechanism to assign Trace ID values to sources is limited
> > and does not scale for larger multicore / multi trace source systems.
> >
> > The API introduces functions that reserve IDs based on availabilty
> > represented by a coresight_trace_id_map structure. This records the
> > used and free IDs in a bitmap.
> >
> > CPU bound sources such as ETMs use the coresight_trace_id_get_cpu_id
> > coresight_trace_id_put_cpu_id pair of functions. The API will record
> > the ID associated with the CPU. This ensures that the same ID will be
> > re-used while perf events are active on the CPU. The put_cpu_id function
> > will pend release of the ID until all perf cs_etm sessions are complete.
> >
> > For backward compatibility the functions will attempt to use the same
> > CPU IDs as the legacy system would have used if these are still available.
> >
> > Non-cpu sources, such as the STM can use coresight_trace_id_get_system_id /
> > coresight_trace_id_put_system_id.
> >
> > Signed-off-by: Mike Leach <mike.leach@linaro.org>
> > ---
> >   drivers/hwtracing/coresight/Makefile          |   2 +-
> >   .../hwtracing/coresight/coresight-trace-id.c  | 265 ++++++++++++++++++
> >   .../hwtracing/coresight/coresight-trace-id.h  | 156 +++++++++++
> >   include/linux/coresight-pmu.h                 |  10 +
> >   4 files changed, 432 insertions(+), 1 deletion(-)
> >   create mode 100644 drivers/hwtracing/coresight/coresight-trace-id.c
> >   create mode 100644 drivers/hwtracing/coresight/coresight-trace-id.h
> >
> > diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> > index b6c4a48140ec..329a0c704b87 100644
> > --- a/drivers/hwtracing/coresight/Makefile
> > +++ b/drivers/hwtracing/coresight/Makefile
> > @@ -6,7 +6,7 @@ obj-$(CONFIG_CORESIGHT) += coresight.o
> >   coresight-y := coresight-core.o  coresight-etm-perf.o coresight-platform.o \
> >               coresight-sysfs.o coresight-syscfg.o coresight-config.o \
> >               coresight-cfg-preload.o coresight-cfg-afdo.o \
> > -             coresight-syscfg-configfs.o
> > +             coresight-syscfg-configfs.o coresight-trace-id.o
> >   obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o
> >   coresight-tmc-y := coresight-tmc-core.o coresight-tmc-etf.o \
> >                     coresight-tmc-etr.o
> > diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/drivers/hwtracing/coresight/coresight-trace-id.c
> > new file mode 100644
> > index 000000000000..9b85c376cb12
> > --- /dev/null
> > +++ b/drivers/hwtracing/coresight/coresight-trace-id.c
> > @@ -0,0 +1,265 @@
> > +// SPDX-License-Identifier: GPL-2.0
>
> ...
>
> > +int coresight_trace_id_read_cpu_id(int cpu)
> > +{
> > +     return _coresight_trace_id_read_cpu_id(cpu);
> > +}
> > +EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id);
> > +
> > +int coresight_trace_id_get_system_id(void)
> > +{
> > +     return coresight_trace_id_map_get_system_id(&id_map_default);
> > +}
> > +EXPORT_SYMBOL_GPL(coresight_trace_id_get_system_id);
> > +
> > +void coresight_trace_id_put_system_id(int id)
> > +{
> > +     coresight_trace_id_map_put_system_id(&id_map_default, id);
> > +}
> > +EXPORT_SYMBOL_GPL(coresight_trace_id_put_system_id);
> > +
> > +void coresight_trace_id_perf_start(void)
> > +{
> > +     atomic_inc(&perf_cs_etm_session_active);
> > +}
> > +EXPORT_SYMBOL_GPL(coresight_trace_id_perf_start);
> > +
> > +void coresight_trace_id_perf_stop(void)
> > +{
> > +     if (!atomic_dec_return(&perf_cs_etm_session_active))
> > +             coresight_trace_id_release_all_pending();
> > +}
> > +EXPORT_SYMBOL_GPL(coresight_trace_id_perf_stop);
> > +
>
> This blank new line at the end of the file generates a checkpatch
> warning for me. I have fixed it locally and applied it.
>
OK, thanks.

The only thing I get out of checkpatch.pl for this patch (and indeed
the entire set) is:

WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?

Mike

> > diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/drivers/hwtracing/coresight/coresight-trace-id.h
>
>


-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK