Re: [PATCH V3 06/14] dts: bindings: Document device tree bindings for ETE
From: Suzuki K Poulose
Date: Thu Feb 18 2021 - 17:53:07 EST
On 2/18/21 6:33 PM, Rob Herring wrote:
On Wed, Feb 10, 2021 at 12:33:44PM +0000, Suzuki K Poulose wrote:
Hi Rob
On 2/9/21 7:00 PM, Rob Herring wrote:
On Wed, Jan 27, 2021 at 02:25:30PM +0530, Anshuman Khandual wrote:
From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Document the device tree bindings for Embedded Trace Extensions.
ETE can be connected to legacy coresight components and thus
could optionally contain a connection graph as described by
the CoreSight bindings.
Cc: devicetree@xxxxxxxxxxxxxxx
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
Changes in V3:
- Fixed all DT yaml semantics problems
Documentation/devicetree/bindings/arm/ete.yaml | 74 ++++++++++++++++++++++++++
1 file changed, 74 insertions(+)
create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml
diff --git a/Documentation/devicetree/bindings/arm/ete.yaml b/Documentation/devicetree/bindings/arm/ete.yaml
new file mode 100644
index 0000000..edc1fe2
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/ete.yaml
@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
+# Copyright 2021, Arm Ltd
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/arm/ete.yaml#";
+$schema: "http://devicetree.org/meta-schemas/core.yaml#";
+
+title: ARM Embedded Trace Extensions
+
+maintainers:
+ - Suzuki K Poulose <suzuki.poulose@xxxxxxx>
+ - Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
+
+description: |
+ Arm Embedded Trace Extension(ETE) is a per CPU trace component that
+ allows tracing the CPU execution. It overlaps with the CoreSight ETMv4
+ architecture and has extended support for future architecture changes.
+ The trace generated by the ETE could be stored via legacy CoreSight
+ components (e.g, TMC-ETR) or other means (e.g, using a per CPU buffer
+ Arm Trace Buffer Extension (TRBE)). Since the ETE can be connected to
+ legacy CoreSight components, a node must be listed per instance, along
+ with any optional connection graph as per the coresight bindings.
+ See bindings/arm/coresight.txt.
+
+properties:
+ $nodename:
+ pattern: "^ete([0-9a-f]+)$"
+ compatible:
+ items:
+ - const: arm,embedded-trace-extension
+
+ cpu:
We've already established 'cpus' for this purpose.
Please see : https://lkml.kernel.org/r/9417218b-6eda-373b-a2cb-869089ffc7cd@xxxxxxx
for my response in the previous version to this and the one with out-ports.
Okay, fair enough.
+ description: |
+ Handle to the cpu this ETE is bound to.
+ $ref: /schemas/types.yaml#/definitions/phandle
+
+ out-ports:
+ type: object
Replace with: $ref: /schemas/graph.yaml#/properties/ports
So, just to confirm again :
The CoreSight graph bindings expect the input ports and output ports
grouped under in-ports{} and out-ports{} respectively to avoid having
to specify the direction of the ports in the individual "port" nodes.
i.e
in-ports {
property: ports
OR
property: port
required:
OneOf:
ports
port
No, 'ports' as a child of in-ports is not correct. There should only be
'port(@[0-9a-f]+)?' nodes. That's why you need the above $ref added. The
$ref doesn't define the node name is 'ports', but what a 'ports' or
'foo-ports' contains.
Sorry, it is my bad. We don't expect ports{} under in-ports. So your
suggestion is the accurate one. I will respin.
}
out-ports {
# same as above
}
So thats why I added out-ports as a new object, where the ports/port
could be a child node.
Ideally the definition of out-ports /in-ports should go to a common schema
for CoreSight bindings, when we move to Yaml for the existing bindings,
which will follow in a separate series, later.
Yes, maybe, but I'm not sure something common is going to help here.
You'll still have to describe what each 'port' node does in each device
specific binding.
For CoreSight components the end-point of the ports are system specific.
i.e, it could be anything on the other end. There is no fixed end-point
connection.
e.g, ETM could be connected to a Replicator or a Funnel. Same as here
above for ETE. Thus the driver must parse the endpoints and make
the connection path from devices to other devices.
Anyways, will come to that in a different series.
I will fix the in-ports/out-ports for the next version.
Thanks for your guidance.
Cheers
Suzuki
Rob