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.
--
~Randy
