Re: [PATCH v2 5/5] Documentation: coresight: Update coresight configuration docs

[Mike Leach <mike.leach@linaro.org>]

Hi German,


On Wed, 20 Oct 2021 at 11:08, German Gomez <german.gomez@arm.com> wrote:
>
> Hi Mike,
>
> Sorry if this is the wrong channel to report this, but is the section in

This is exactly the right place to report this!

> the coresight-config configuration, where it lists "configurations"
> under the "/sys/devices/cs_etm/" directory still relevant?
>
>     $ ls /sys/devices/cs_etm
>     configurations  format  perf_event_mux_interval_ms  sinks  type
>     events  nr_addr_filters  power
>
> I think it may have been removed in a previous patchset [1]. I didn't
> see it when trying the coresight-config patches.
>
>     2) Dropped the 'configurations' sub dir in cs_etm perf directories as superfluous
>

I think you are correct - I haven't got access to my target to
confirm, but I do remember removing this directory - so the docs do
need updating.
I'll either fix on a respin of this set, or generate a separate patch.

Thanks for spotting this.

Mike


> Thanks,
> German
>
> [1] https://lore.kernel.org/linux-arm-kernel/20210707133003.5414-1-mike.leach@linaro.org/
>
> On 19/10/2021 20:13, Mike Leach wrote:
> > Update the CoreSight System Configuration document to cover the
> > use of loadable modules to add configurations and features
> > to the system.
> >
> > Signed-off-by: Mike Leach <mike.leach@linaro.org>
> > ---
> >  .../trace/coresight/coresight-config.rst      | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst
> > index a4e3ef295240..911db4da7f99 100644
> > --- a/Documentation/trace/coresight/coresight-config.rst
> > +++ b/Documentation/trace/coresight/coresight-config.rst
> > @@ -242,3 +242,22 @@ A preset to override the current parameter values can also be selected::
> >
> >  When configurations are selected in this way, then the trace sink used is
> >  automatically selected.
> > +
> > +Creating and Loading Custom Configurations
> > +==========================================
> > +
> > +Custom configurations and / or features can be dynamically loaded into the
> > +system by using a loadable module.
> > +
> > +An example of a custom configuration is found in ./samples/coresight.
> > +
> > +This creates a new configuration that uses the existing built in
> > +strobing feature, but provides a different set of presets.
> > +
> > +When the module is loaded, then the configuration appears in the configfs
> > +file system and is selectable in the same way as the built in configuration
> > +described above.
> > +
> > +Configurations can use previously loaded features. The system will ensure
> > +that it is not possible to unload a feature that is currently in use, by
> > +enforcing the unload order as the strict reverse of the load order.



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

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