From: Mike Leach <mike.leach@linaro.org>
To: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org
Cc: mathieu.poirier@linaro.org, suzuki.poulose@arm.com,
leo.yan@linaro.org, Mike Leach <mike.leach@linaro.org>
Subject: [PATCH v3 6/6] Documentation: coresight: Update coresight configuration docs
Date: Wed, 24 Nov 2021 20:00:38 +0000 [thread overview]
Message-ID: <20211124200038.28662-7-mike.leach@linaro.org> (raw)
In-Reply-To: <20211124200038.28662-1-mike.leach@linaro.org>
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 | 62 ++++++++++++++++++-
1 file changed, 59 insertions(+), 3 deletions(-)
diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst
index 6ed13398ca2c..6d5ffa6f7347 100644
--- a/Documentation/trace/coresight/coresight-config.rst
+++ b/Documentation/trace/coresight/coresight-config.rst
@@ -155,14 +155,14 @@ follows::
autofdo
$ cd autofdo/
$ ls
- description preset1 preset3 preset5 preset7 preset9
- feature_refs preset2 preset4 preset6 preset8
+ description feature_refs preset1 preset3 preset5 preset7 preset9
+ enable preset preset2 preset4 preset6 preset8
$ cat description
Setup ETMs with strobing for autofdo
$ cat feature_refs
strobing
-Each preset declared has a preset<n> subdirectory declared. The values for
+Each preset declared has a 'preset<n>' subdirectory declared. The values for
the preset can be examined::
$ cat preset1/values
@@ -170,6 +170,9 @@ the preset can be examined::
$ cat preset2/values
strobing.window = 0x1388 strobing.period = 0x4
+The 'enable' and 'preset' files allow the control of a configuration when
+using CoreSight with sysfs.
+
The features referenced by the configuration can be examined in the features
directory::
@@ -236,3 +239,56 @@ 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.
+
+Using Configurations in sysfs
+=============================
+
+Coresight can be controlled using sysfs. When this is in use then a configuration
+can be made active for the devices that are used in the sysfs session.
+
+In a configuration there are 'enable' and 'preset' files.
+
+To enable a configuration for use with sysfs::
+
+ $ cd configurations/autofdo
+ $ echo 1 > enable
+
+This will then use any default parameter values in the features - which can be
+adjusted as described above.
+
+To use a preset<n> set of parameter values::
+
+ $ echo 3 > preset
+
+This will select preset3 for the configuration.
+The valid values for preset are 0 - to deselect presets, and any value of
+<n> where a preset<n> sub-directory is present.
+
+Note that the active sysfs configuration is a global parameter, therefore
+only a single configuration can be active for sysfs at any one time.
+Attempting to enable a second configuration will result in an error.
+Additionally, attempting to disable the configuration while in use will
+also result in an error.
+
+The use of the active configuration by sysfs is independent of the configuration
+used in perf.
+
+
+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.
--
2.17.1
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next prev parent reply other threads:[~2021-11-24 20:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-24 20:00 [PATCH v3 0/6] coresight: syscfg: dynamic load Mike Leach
2021-11-24 20:00 ` [PATCH v3 1/6] coresight: configuration: Update API to introduce load owner concept Mike Leach
2021-11-24 20:00 ` [PATCH v3 2/6] coresight: configuration: Update API to permit dynamic load/unload Mike Leach
2021-11-24 20:00 ` [PATCH v3 3/6] coresight: syscfg: Update load API for config loadable modules Mike Leach
2021-11-24 20:00 ` [PATCH v3 4/6] coresight: syscfg: Example CoreSight configuration loadable module Mike Leach
2021-11-26 18:23 ` Mathieu Poirier
2021-11-29 12:24 ` Mike Leach
2021-11-29 16:44 ` Mathieu Poirier
2021-11-24 20:00 ` [PATCH v3 5/6] coresight: configfs: Allow configfs to activate configuration Mike Leach
2021-11-24 20:00 ` Mike Leach [this message]
2021-11-26 18:26 ` [PATCH v3 6/6] Documentation: coresight: Update coresight configuration docs Mathieu Poirier
2021-11-29 11:54 ` Mike Leach
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