[PATCH v1 0/3] Add support to configure Coresight Dummy subunit

[PATCH v1 0/3] Add support to configure Coresight Dummy subunit

[Hao Zhang]

Introduction of Coresight Dummy subunit
The Coresight Dummy subunit is for Coresight Dummy component, there are some
specific Coresight devices that HLOS don't have permission to access. Such as
some TPDMs, they would be configured in NON-HLOS side, but it's necessary to
build Coresight path for it to debug. So there need driver to register dummy
devices as Coresight devices.

Commit link:
https://git.codelinaro.org/clo/linux-kernel/coresight/-/tree/coresight-dummy

Hao Zhang (3):
  Coresight: Add coresight dummy driver
  dt-bindings: arm: Add Coresight Dummy Trace YAML schema
  Documentation: trace: Add documentation for Coresight Dummy Trace

 .../bindings/arm/qcom,coresight-dummy.yaml    | 129 +++++++++++++
 .../trace/coresight/coresight-dummy.rst       |  58 ++++++
 drivers/hwtracing/coresight/Kconfig           |  11 ++
 drivers/hwtracing/coresight/Makefile          |   1 +
 drivers/hwtracing/coresight/coresight-dummy.c | 176 ++++++++++++++++++
 5 files changed, 375 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
 create mode 100644 Documentation/trace/coresight/coresight-dummy.rst
 create mode 100644 drivers/hwtracing/coresight/coresight-dummy.c

-- 
2.17.1

[PATCH v1 1/3] Coresight: Add coresight dummy driver

[Hao Zhang]

Some Coresight devices that HLOS don't have permission to access
or configure. Such as Coresight sink EUD, some TPDMs etc. So there
need driver to register dummy devices as Coresight devices. Provide
Coresight API for dummy device operations, such as enabling and
disabling dummy devices. Build the Coresight path for dummy sink or
dummy source for debugging.

Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
---
 drivers/hwtracing/coresight/Kconfig           |  11 ++
 drivers/hwtracing/coresight/Makefile          |   1 +
 drivers/hwtracing/coresight/coresight-dummy.c | 176 ++++++++++++++++++
 3 files changed, 188 insertions(+)
 create mode 100644 drivers/hwtracing/coresight/coresight-dummy.c

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 2b5bbfffbc4f..06f0a7594169 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -236,4 +236,15 @@ config CORESIGHT_TPDA
 
 	  To compile this driver as a module, choose M here: the module will be
 	  called coresight-tpda.
+
+config CORESIGHT_DUMMY
+	tristate "Dummy driver support"
+	help
+	  Enables support for dummy driver. Dummy driver can be used for
+	  CoreSight sources/sinks that are owned and configured by some
+	  other subsystem and use Linux drivers to configure rest of trace
+	  path.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called coresight-dummy.
 endif
diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 33bcc3f7b8ae..995d3b2c76df 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -30,3 +30,4 @@ obj-$(CONFIG_CORESIGHT_TPDA) += coresight-tpda.o
 coresight-cti-y := coresight-cti-core.o	coresight-cti-platform.o \
 		   coresight-cti-sysfs.o
 obj-$(CONFIG_ULTRASOC_SMB) += ultrasoc-smb.o
+obj-$(CONFIG_CORESIGHT_DUMMY) += coresight-dummy.o
diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/hwtracing/coresight/coresight-dummy.c
new file mode 100644
index 000000000000..d06baafb77da
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-dummy.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/coresight.h>
+#include <linux/of.h>
+#include <linux/pm_runtime.h>
+
+#include "coresight-priv.h"
+#include "coresight-trace-id.h"
+
+struct dummy_drvdata {
+	struct device			*dev;
+	struct coresight_device		*csdev;
+	int				traceid;
+};
+
+DEFINE_CORESIGHT_DEVLIST(dummy_devs, "dummy");
+
+static int dummy_source_enable(struct coresight_device *csdev,
+			       struct perf_event *event, u32 mode)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy source enabled\n");
+
+	return 0;
+}
+
+static void dummy_source_disable(struct coresight_device *csdev,
+				 struct perf_event *event)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy source disabled\n");
+}
+
+static int dummy_sink_enable(struct coresight_device *csdev, u32 mode,
+				void *data)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy sink enabled\n");
+
+	return 0;
+}
+
+static int dummy_sink_disable(struct coresight_device *csdev)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy sink disabled\n");
+
+	return 0;
+}
+
+static const struct coresight_ops_source dummy_source_ops = {
+	.enable		= dummy_source_enable,
+	.disable	= dummy_source_disable,
+};
+
+static const struct coresight_ops_sink dummy_sink_ops = {
+	.enable		= dummy_sink_enable,
+	.disable	= dummy_sink_disable,
+};
+
+static const struct coresight_ops dummy_cs_ops = {
+	.source_ops	= &dummy_source_ops,
+	.sink_ops	= &dummy_sink_ops,
+};
+
+static int dummy_probe(struct platform_device *pdev)
+{
+	int ret, trace_id;
+	struct device *dev = &pdev->dev;
+	struct coresight_platform_data *pdata;
+	struct dummy_drvdata *drvdata;
+	struct coresight_desc desc = { 0 };
+
+	desc.name = coresight_alloc_device_name(&dummy_devs, dev);
+	if (!desc.name)
+		return -ENOMEM;
+
+	pdata = coresight_get_platform_data(dev);
+	if (IS_ERR(pdata))
+		return PTR_ERR(pdata);
+	pdev->dev.platform_data = pdata;
+
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	drvdata->dev = &pdev->dev;
+	platform_set_drvdata(pdev, drvdata);
+
+	if (of_property_read_bool(pdev->dev.of_node, "qcom,dummy-source")) {
+		desc.type = CORESIGHT_DEV_TYPE_SOURCE;
+		desc.subtype.source_subtype =
+					CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS;
+	} else if (of_property_read_bool(pdev->dev.of_node,
+					 "qcom,dummy-sink")) {
+		desc.type = CORESIGHT_DEV_TYPE_SINK;
+		desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
+	} else {
+		dev_info(dev, "Device type not set\n");
+		return -EINVAL;
+	}
+
+	desc.ops = &dummy_cs_ops;
+	desc.pdata = pdev->dev.platform_data;
+	desc.dev = &pdev->dev;
+	drvdata->csdev = coresight_register(&desc);
+	if (IS_ERR(drvdata->csdev))
+		return PTR_ERR(drvdata->csdev);
+
+	trace_id = coresight_trace_id_get_system_id();
+	if (trace_id < 0) {
+		ret = trace_id;
+		goto cs_unregister;
+	}
+	drvdata->traceid = (u8)trace_id;
+
+	pm_runtime_enable(dev);
+	dev_info(dev, "Dummy device initialized\n");
+
+	return 0;
+
+cs_unregister:
+	coresight_unregister(drvdata->csdev);
+
+	return ret;
+}
+
+static int dummy_remove(struct platform_device *pdev)
+{
+	struct dummy_drvdata *drvdata = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+
+	coresight_trace_id_put_system_id(drvdata->traceid);
+	pm_runtime_disable(dev);
+	coresight_unregister(drvdata->csdev);
+	return 0;
+}
+
+static const struct of_device_id dummy_match[] = {
+	{.compatible = "qcom,coresight-dummy"},
+	{},
+};
+
+static struct platform_driver dummy_driver = {
+	.probe	= dummy_probe,
+	.remove	= dummy_remove,
+	.driver	= {
+		.name   = "coresight-dummy",
+		.of_match_table = dummy_match,
+	},
+};
+
+int __init dummy_init(void)
+{
+	return platform_driver_register(&dummy_driver);
+}
+module_init(dummy_init);
+
+void __exit dummy_exit(void)
+{
+	platform_driver_unregister(&dummy_driver);
+}
+module_exit(dummy_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CoreSight dummy source driver");
-- 
2.17.1

[PATCH v1 2/3] dt-bindings: arm: Add Coresight Dummy Trace YAML schema

[Hao Zhang]

Add new coresight-dummy.yaml file describing the bindings required
to define coresight dummy trace in the device trees.

Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
---
 .../bindings/arm/qcom,coresight-dummy.yaml    | 129 ++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml

diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
new file mode 100644
index 000000000000..3a7f98df2ee9
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
@@ -0,0 +1,129 @@
+# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
+# Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/qcom,coresight-dummy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: QCOM Coresight Dummy component
+
+description: |
+  The Coresight Dummy component is for the specific devices that HLOS don't have
+  permission to access or configure. Such as Coresight sink EUD, some TPDMs etc.
+  So there need driver to register dummy devices as Coresight devices. Provide
+  Coresight API for dummy device operations, such as enabling and disabling
+  dummy devices. Build the Coresight path for dummy sink or dummy source for
+  debugging.
+
+  The primary use case of the coresight dummy is to build path for dummy sink or
+  dummy source.
+
+maintainers:
+  - Mao Jinlong <quic_jinlmao@quicinc.com>
+  - Tao Zhang <quic_taozha@quicinc.com>
+  - Hao Zhang <quic_hazha@quicinc.com>
+
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - qcom,coresight-dummy
+  required:
+    - compatible
+
+properties:
+  $nodename:
+    pattern: "^dummy(@[0-9a-f]+)$"
+  compatible:
+    items:
+      - const: qcom,coresight-dummy
+
+  reg:
+    minItems: 1
+    maxItems: 2
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: apb_pclk
+
+  qcom,dummy-sink:
+    type: boolean
+    description:
+      Indicates that the type of this coresight node is dummy sink.
+
+  qcom,dummy-source:
+    type: boolean
+    description:
+      Indicates that the type of this coresight node is dummy source.
+
+  out-ports:
+    description: |
+      Output connections from the dummy source to Coresight Trace bus.
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port:
+        description: Output connection from the dummy source to Coresight
+            Trace bus.
+        $ref: /schemas/graph.yaml#/properties/port
+
+  in-puts:
+    description: |
+      Input connections from the CoreSight Trace bus to dummy sink.
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port:
+        description: Input connection from the Coresight Trace bus to
+            dummy sink.
+        $ref: /schemas/graph.yaml#/properties/port
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - oneOf:
+    - qcom,dummy-sink
+    - qcom,dummy-source
+
+additionalProperties: false
+
+examples:
+  # minimum dummy sink definition. dummy sink connect to coresight replicator.
+  - |
+    dummy_eud: dummy_sink {
+      compatible = "qcom,dummy";
+      qcom,dummy-sink;
+
+      in-ports {
+        port {
+          eud_in_replicator_swao: endpoint {
+            remote-endpoint =
+              <&replicator_swao_out_eud>;
+          };
+        };
+      };
+    };
+
+  # minimum dummy source definition. dummy source connect to coresight funnel.
+  - |
+    dummy_riscv: dummy_source {
+      compatible = "qcom,dummy";
+      qcom,dummy-source;
+
+      out-ports {
+        port {
+          dummy_riscv_out_funnel_swao: endpoint {
+            remote-endpoint =
+              <&funnel_swao_in_dummy_riscv>;
+          };
+        };
+      };
+    };
+
+...
-- 
2.17.1

[PATCH v1 3/3] Documentation: trace: Add documentation for Coresight Dummy Trace

[Hao Zhang]

Add documentation for Coresight Dummy Trace under trace/coresight.

Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
---
 .../trace/coresight/coresight-dummy.rst       | 58 +++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 Documentation/trace/coresight/coresight-dummy.rst

diff --git a/Documentation/trace/coresight/coresight-dummy.rst b/Documentation/trace/coresight/coresight-dummy.rst
new file mode 100644
index 000000000000..819cabab8623
--- /dev/null
+++ b/Documentation/trace/coresight/coresight-dummy.rst
@@ -0,0 +1,58 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+Coresight Dummy Trace Module
+=============================
+
+    :Author:   Hao Zhang <quic_hazha@quicinc.com>
+    :Date:     March 2023
+
+Introduction
+---------------------------
+
+Coresight Dummy Trace Module is for the specific devices that HLOS don't
+have permission to access or configure. Such as Coresight sink EUD, some
+TPDMs etc. So there need driver to register dummy devices as Coresight
+devices. Provide Coresight API for dummy device operations, such as
+enabling and disabling dummy devices. Build the Coresight path for dummy
+sink or dummy source for debugging.
+
+Sysfs files and directories
+---------------------------
+
+Root: ``/sys/bus/coresight/devices/dummy<N>``
+
+----
+
+:File:            ``enable_source`` (RW)
+:Notes:
+    - > 0 : enable the datasets of dummy source.
+
+    - = 0 : disable the datasets of dummy source.
+
+:Syntax:
+    ``echo 1 > enable_source``
+
+----
+
+:File:            ``enable_sink`` (RW)
+:Notes:
+    - > 0 : enable the datasets of dummy sink.
+
+    - = 0 : disable the datasets of dummy sink.
+
+:Syntax:
+    ``echo 1 > enable_sink``
+
+----
+
+Config details
+---------------------------
+
+There are two types of nodes, dummy sink and dummy source. The nodes
+should be observed at the coresight path
+"/sys/bus/coresight/devices".
+e.g.
+/sys/bus/coresight/devices # ls -l | grep dummy
+dummy0 -> ../../../devices/platform/soc@0/soc@0:dummy_source/dummy0
+dummy1 -> ../../../devices/platform/soc@0/soc@0:dummy_sink/dummy1
-- 
2.17.1

Re: [PATCH v1 1/3] Coresight: Add coresight dummy driver

[kernel test robot]

Hi Hao,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on robh/for-next]
[also build test WARNING on linus/master v6.3-rc2 next-20230316]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Hao-Zhang/Coresight-Add-coresight-dummy-driver/20230316-112827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/20230316032005.6509-2-quic_hazha%40quicinc.com
patch subject: [PATCH v1 1/3] Coresight: Add coresight dummy driver
config: arm-allyesconfig (https://download.01.org/0day-ci/archive/20230316/202303161702.oIkvUip5-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/140cd28ed9031020826cfb5e62e80e28f7504895
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Hao-Zhang/Coresight-Add-coresight-dummy-driver/20230316-112827
        git checkout 140cd28ed9031020826cfb5e62e80e28f7504895
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/hwtracing/coresight/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303161702.oIkvUip5-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/hwtracing/coresight/coresight-dummy.c:163:12: warning: no previous prototype for 'dummy_init' [-Wmissing-prototypes]
     163 | int __init dummy_init(void)
         |            ^~~~~~~~~~
>> drivers/hwtracing/coresight/coresight-dummy.c:169:13: warning: no previous prototype for 'dummy_exit' [-Wmissing-prototypes]
     169 | void __exit dummy_exit(void)
         |             ^~~~~~~~~~


vim +/dummy_init +163 drivers/hwtracing/coresight/coresight-dummy.c

   162	
 > 163	int __init dummy_init(void)
   164	{
   165		return platform_driver_register(&dummy_driver);
   166	}
   167	module_init(dummy_init);
   168	
 > 169	void __exit dummy_exit(void)
   170	{
   171		platform_driver_unregister(&dummy_driver);
   172	}
   173	module_exit(dummy_exit);
   174	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

Re: [PATCH v1 0/3] Add support to configure Coresight Dummy subunit

[Suzuki K Poulose]

On 16/03/2023 03:20, Hao Zhang wrote:
> Introduction of Coresight Dummy subunit
> The Coresight Dummy subunit is for Coresight Dummy component, there are some
> specific Coresight devices that HLOS don't have permission to access. Such as

What is HLOS ?

> some TPDMs, they would be configured in NON-HLOS side, but it's necessary to

What is NON-HLOS ?

> build Coresight path for it to debug. So there need driver to register dummy
> devices as Coresight devices.

Build a path for who to debug ? If this is used by some privileged
software, shouldn't that do all of the work ?

Suzuki

> 
> Commit link:
> https://git.codelinaro.org/clo/linux-kernel/coresight/-/tree/coresight-dummy
> 
> Hao Zhang (3):
>    Coresight: Add coresight dummy driver
>    dt-bindings: arm: Add Coresight Dummy Trace YAML schema
>    Documentation: trace: Add documentation for Coresight Dummy Trace
> 
>   .../bindings/arm/qcom,coresight-dummy.yaml    | 129 +++++++++++++
>   .../trace/coresight/coresight-dummy.rst       |  58 ++++++
>   drivers/hwtracing/coresight/Kconfig           |  11 ++
>   drivers/hwtracing/coresight/Makefile          |   1 +
>   drivers/hwtracing/coresight/coresight-dummy.c | 176 ++++++++++++++++++
>   5 files changed, 375 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
>   create mode 100644 Documentation/trace/coresight/coresight-dummy.rst
>   create mode 100644 drivers/hwtracing/coresight/coresight-dummy.c
> 

Re: [PATCH v1 2/3] dt-bindings: arm: Add Coresight Dummy Trace YAML schema

[Rob Herring]

On Thu, 16 Mar 2023 11:20:04 +0800, Hao Zhang wrote:
> Add new coresight-dummy.yaml file describing the bindings required
> to define coresight dummy trace in the device trees.
> 
> Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
> ---
>  .../bindings/arm/qcom,coresight-dummy.yaml    | 129 ++++++++++++++++++
>  1 file changed, 129 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml:91:5: [warning] wrong indentation: expected 6 but found 4 (indentation)

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml: required:4: {'oneOf': ['qcom,dummy-sink', 'qcom,dummy-source']} is not of type 'string'
	from schema $id: http://json-schema.org/draft-07/schema#
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml: ignoring, error in schema: required: 4
Documentation/devicetree/bindings/arm/qcom,coresight-dummy.example.dtb: /example-0/dummy_sink: failed to match any schema with compatible: ['qcom,dummy']
Documentation/devicetree/bindings/arm/qcom,coresight-dummy.example.dtb: /example-1/dummy_source: failed to match any schema with compatible: ['qcom,dummy']

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20230316032005.6509-3-quic_hazha@quicinc.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH v1 0/3] Add support to configure Coresight Dummy subunit

[Hao Zhang]

Hi Suzuki,

On 3/16/2023 6:55 PM, Suzuki K Poulose wrote:
> On 16/03/2023 03:20, Hao Zhang wrote:
>> Introduction of Coresight Dummy subunit
>> The Coresight Dummy subunit is for Coresight Dummy component, there 
>> are some
>> specific Coresight devices that HLOS don't have permission to access. 
>> Such as
> 
> What is HLOS ?

The term HLOS stands for High Level OS, it means linux in this case. The 
HLOS runs on APPS processor.

>> some TPDMs, they would be configured in NON-HLOS side, but it's 
>> necessary to
> 
> What is NON-HLOS ?

There are some other sub-processors like modem, adsp etc, they do not 
have a High Level OS. The OS in these sub-processors is lightweight, 
less powerful, somewhat real-time, it would be called NON-HLOS.

>> build Coresight path for it to debug. So there need driver to register 
>> dummy
>> devices as Coresight devices.
> 
> Build a path for who to debug ? If this is used by some privileged
> software, shouldn't that do all of the work ?
> 
> Suzuki

There is coresight source or sink in sub-processor, it would be 
configured by NON-HLOS, and need HLOS to configure the last coresight 
components. So we will use dummy source or sink to replace it in HLOS 
side for building the whole path(from source to sink).

Thanks,
Hao

>>
>> Commit link:
>> https://git.codelinaro.org/clo/linux-kernel/coresight/-/tree/coresight-dummy
>>
>> Hao Zhang (3):
>>    Coresight: Add coresight dummy driver
>>    dt-bindings: arm: Add Coresight Dummy Trace YAML schema
>>    Documentation: trace: Add documentation for Coresight Dummy Trace
>>
>>   .../bindings/arm/qcom,coresight-dummy.yaml    | 129 +++++++++++++
>>   .../trace/coresight/coresight-dummy.rst       |  58 ++++++
>>   drivers/hwtracing/coresight/Kconfig           |  11 ++
>>   drivers/hwtracing/coresight/Makefile          |   1 +
>>   drivers/hwtracing/coresight/coresight-dummy.c | 176 ++++++++++++++++++
>>   5 files changed, 375 insertions(+)
>>   create mode 100644 
>> Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
>>   create mode 100644 Documentation/trace/coresight/coresight-dummy.rst
>>   create mode 100644 drivers/hwtracing/coresight/coresight-dummy.c
>>
> 

Re: [PATCH v1 2/3] dt-bindings: arm: Add Coresight Dummy Trace YAML schema

[Hao Zhang]

On 3/16/2023 9:53 PM, Rob Herring wrote:
> 
> On Thu, 16 Mar 2023 11:20:04 +0800, Hao Zhang wrote:
>> Add new coresight-dummy.yaml file describing the bindings required
>> to define coresight dummy trace in the device trees.
>>
>> Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
>> ---
>>   .../bindings/arm/qcom,coresight-dummy.yaml    | 129 ++++++++++++++++++
>>   1 file changed, 129 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml
>>
> 
> My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> on your patch (DT_CHECKER_FLAGS is new in v5.13):
> 
> yamllint warnings/errors:
> ./Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml:91:5: [warning] wrong indentation: expected 6 but found 4 (indentation)
> 
> dtschema/dtc warnings/errors:
> /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml: required:4: {'oneOf': ['qcom,dummy-sink', 'qcom,dummy-source']} is not of type 'string'
> 	from schema $id: http://json-schema.org/draft-07/schema#
> /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/arm/qcom,coresight-dummy.yaml: ignoring, error in schema: required: 4
> Documentation/devicetree/bindings/arm/qcom,coresight-dummy.example.dtb: /example-0/dummy_sink: failed to match any schema with compatible: ['qcom,dummy']
> Documentation/devicetree/bindings/arm/qcom,coresight-dummy.example.dtb: /example-1/dummy_source: failed to match any schema with compatible: ['qcom,dummy']
> 
> doc reference errors (make refcheckdocs):
> 
> See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20230316032005.6509-3-quic_hazha@quicinc.com
> 
> The base for the series is generally the latest rc1. A different dependency
> should be noted in *this* patch.
> 
> If you already ran 'make dt_binding_check' and didn't see the above
> error(s), then make sure 'yamllint' is installed and dt-schema is up to
> date:
> 
> pip3 install dtschema --upgrade
> 
> Please check and re-submit after running the above command yourself. Note
> that DT_SCHEMA_FILES can be set to your schema file to speed up checking
> your schema. However, it must be unset to test all examples with your schema.
> 

Hi Rob,

Thanks for your check.
I have checked it and didn't see the above errors, will follow your 
steps and change this in the next version of patch.

Thanks,
Hao