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SubjectRe: [TEGRA194_CPUFREQ PATCH v5 1/4] dt-bindings: arm: Add t194 ccplex compatible and bpmp property
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> On Mon, Jul 13, 2020 at 07:36:46PM +0530, Sumit Gupta wrote:
>> 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.

>>
>> 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]

>> - 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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