On 1/30/2026 2:38 AM, Randy Dunlap wrote:
On 1/29/26 10:31 AM, Randy Dunlap wrote:
diff --git a/Documentation/trace/p_ost.rst b/Documentation/trace/p_ost.rst
new file mode 100644
index 000000000000..df93b889eb4c
--- /dev/null
+++ b/Documentation/trace/p_ost.rst
@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================
+MIPI OST over STP
+===================
+
+The OST(Open System Trace) driver is used with STM class devices to
The OST (Open System Trace) driver
+generate standardized trace stream. Trace sources can be identified
+by different entity ids.
+
+CONFIG_STM_PROTO_OST is for p_ost driver enablement. Once this config
+is enabled, you can select the p_ost protocol by command below:
+
+# mkdir /sys/kernel/config/stp-policy/stm0:p_ost.policy
+
+The policy name format is extended like this:
+ <device_name>:<protocol_name>.<policy_name>
+
+With coresight-stm device, it will be look like "stm0:p_ost.policy".
With {a | the} coresight-stm device,
+
+With MIPI OST protocol driver, the attributes for each protocol node is:
With the MIPI OST protocol driver, are:
+# mkdir /sys/kernel/config/stp-policy/stm0:p_ost.policy/default
+# ls /sys/kernel/config/stp-policy/stm0:p_ost.policy/default
+channels entity masters
+
+The entity here is the set the entity that p_ost supports. Currently
is the set of {entities | features} that p_ost supports.
Currently
+p_ost supports ftrace, console and diag entity.
entities.
+
+Set entity:
+# echo 'ftrace' >
/sys/kernel/config/stp-policy/stm0:p_ost.policy/default/entity
+
+Get available and currently selected (shown in square brackets) entity that
p_ost supports:
+# cat /sys/kernel/config/stp-policy/stm0:p_ost.policy/default/entity
+[ftrace] console diag
+
+See Documentation/ABI/testing/configfs-stp-policy-p_ost for more details.
Thanks, will update.
Yingchao
