On Tue, Jul 14, 2020 at 5:44 AM Sumit Gupta [off-list ref] wrote:

quoted

On Mon, Jul 13, 2020 at 07:36:46PM +0530, Sumit Gupta wrote:

quoted

To do frequency scaling on all CPUs within T194 CPU Complex, we need
to query BPMP for data on valid operating points. Document a compatible
string under 'cpus' node to represent the CPU Complex for binding drivers
like cpufreq which don't have their node or CPU Complex node to bind to.
Also, document a property to point to the BPMP device that can be queried
for all CPUs.

The cpus.yaml binding documents what's in 'cpu' nodes, not 'cpus'
node. AIUI, the latter is what you want. You should do your own schema
file here.

Do you mean to change existing file name from 'cpus.yaml' to 'cpu.yaml'
and create new 'cpus.yaml' file?
I think it's better to incorporate the change in existing 'cpus.yaml'
file to keep both cpu@X and cpus node details together. Please suggest.

No, I'm suggesting you create nvidia,tegra194-ccplex.yaml.

quoted

quoted

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
  Documentation/devicetree/bindings/arm/cpus.yaml | 11 +++++++++++
  1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml
index a018147..9b328e3 100644
--- a/Documentation/devicetree/bindings/arm/cpus.yaml
+++ b/Documentation/devicetree/bindings/arm/cpus.yaml

@@ -162,6 +162,7 @@ properties:
        - nvidia,tegra132-denver
        - nvidia,tegra186-denver
        - nvidia,tegra194-carmel
+      - nvidia,tegra194-ccplex

Tegra194 has 2 different CPUs?

No, T194 SOC has homogeneous architecture with four clusters where each
cluster has two symmetric cores. 'nvidia,tegra194-carmel' compatible
string represents each cpu. 'nvidia,tegra194-ccplex' string represents
the CPU Complex to bind cpufreq driver. The change was done as per
discussion [1]

You are adding the compatible string to the cpu@N node compatible.

quoted

quoted

        - qcom,krait
        - qcom,kryo
        - qcom,kryo260

@@ -255,6 +256,15 @@ properties:

        where voltage is in V, frequency is in MHz.

+  nvidia,bpmp:
+    $ref: '/schemas/types.yaml#/definitions/phandle'
+    description: |
+      Specifies the bpmp node that needs to be queried to get
+      operating point data for all CPUs.
+
+      Optional for systems that have a "compatible"
+      property value of "nvidia,tegra194-ccplex".
+
    power-domains:
      $ref: '/schemas/types.yaml#/definitions/phandle-array'
      description:

@@ -340,6 +350,7 @@ required:

  dependencies:
    rockchip,pmu: [enable-method]
+  nvidia,bpmp: [compatible]

  examples:
    - |
--

2.7.4

[1] https://marc.info/?l=linux-arm-kernel&m=158999171528418&w=2

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