Hi Suzuki,

-----Original Message-----
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Sent: Monday, September 4, 2023 1:57 PM
To: Linu Cherian <redacted>; mike.leach@linaro.org;
james.clark@arm.com; leo.yan@linaro.org
Cc: linux-arm-kernel@lists.infradead.org; coresight@lists.linaro.org; linux-
kernel@vger.kernel.org; robh+dt@kernel.org;
krzysztof.kozlowski+dt@linaro.org; conor+dt@kernel.org;
devicetree@vger.kernel.org; Sunil Kovvuri Goutham
[off-list ref]; George Cherian [off-list ref]
Subject: [EXT] Re: [RFC PATCH v3 1/7] dt-bindings: arm: coresight-tmc: Add
"memory-region" property

External Email

----------------------------------------------------------------------
On 04/09/2023 06:05, Linu Cherian wrote:

quoted

memory-region 0: Reserved trace buffer memory

   TMC ETR: When available, use this reserved memory region for
   trace data capture. Same region is used for trace data
   retention after a panic or watchdog reset.

   TMC ETF: When available, use this reserved memory region for
   trace data retention synced from internal SRAM after a panic or
   watchdog reset.

memory-region 1: Reserved meta data memory

   TMC ETR, ETF: When available, use this memory for register
   snapshot retention synced from hardware registers after a panic
   or watchdog reset.

Instead of having to use a number to map the memory regions, could we use

memory-region-names property to describe the index ? That way it is much
easier to read and is less error prone.

Names could be something like:

tmc-reserved-trace
tmc-reserved-metadata

Ack. Will use names in the next version. Will take care of the suggestions from Rob.

Suzuki

quoted

Signed-off-by: Linu Cherian <redacted>
---
  .../devicetree/bindings/arm/arm,coresight-tmc.yaml  | 13

+++++++++++++

quoted

  1 file changed, 13 insertions(+)

diff --git
a/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
b/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
index cb8dceaca70e..dce54978554a 100644

--- a/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
+++ b/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml

@@ -101,6 +101,17 @@ properties:
            and ETF configurations.
          $ref: /schemas/graph.yaml#/properties/port

+   memory-region:
+    items:
+      - description: Reserved trace buffer memory for ETR and ETF sinks.
+        For ETR, this reserved memory region is used for trace data capture.
+        Same region is used for trace data retention as well after a panic
+        or watchdog reset.
+        For ETF, this reserved memory region is used for retention of trace
+        data synced from internal SRAM after a panic or watchdog reset.
+
+      - description: Reserved meta data memory. Used for ETR and ETF sinks.
+
  required:
    - compatible
    - reg

@@ -115,6 +126,8 @@ examples:
      etr@20070000 {
          compatible = "arm,coresight-tmc", "arm,primecell";
          reg = <0x20070000 0x1000>;
+        memory-region = <&etr_trace_mem_reserved>,
+                       <&etr_mdata_mem_reserved>;

          clocks = <&oscclk6a>;
          clock-names = "apb_pclk";

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