Re: [PATCH v5] stm: class: Add MIPI OST protocol support

[Yingchao Deng (Consultant)]

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