diff mbox series

[TEGRA194_CPUFREQ,v3,1/4] dt-bindings: arm: Add t194 ccplex compatible and bpmp property

Message ID 1592775274-27513-2-git-send-email-sumitg@nvidia.com
State Superseded
Headers show
Series Add cpufreq driver for Tegra194 | expand

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Commit Message

Sumit Gupta June 21, 2020, 9:34 p.m. UTC
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.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 Documentation/devicetree/bindings/arm/cpus.yaml | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Viresh Kumar June 22, 2020, 7:22 a.m. UTC | #1
On 22-06-20, 03:04, 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.

You shouldn't be putting how linux is going to use this information and entries
shouldn't be made just so cpufreq can bind to a driver.

Though I see that this is a real hardware register which you can use to interact
with the firmware ? And so it makes sense to have it, maybe in different form
though.

I will let Rob explain what would be the right way of doing this though.

> 
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> ---
>  Documentation/devicetree/bindings/arm/cpus.yaml | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml
> index a018147..737b55e 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
>        - qcom,krait
>        - qcom,kryo
>        - qcom,kryo260
> @@ -255,6 +256,14 @@ properties:
>  
>        where voltage is in V, frequency is in MHz.
>  
> +  nvidia,bpmp:
> +    $ref: '/schemas/types.yaml#/definitions/phandle'
> +    descrption: |
> +      Specifies the bpmp node that needs to be queried to get
> +      operating point data for all CPUs.
> +
> +      Optional for NVIDIA Tegra194 Carmel CPUs
> +
>    power-domains:
>      $ref: '/schemas/types.yaml#/definitions/phandle-array'
>      description:
> -- 
> 2.7.4
Sumit Gupta June 23, 2020, 6:05 a.m. UTC | #2
On 22/06/20 12:52 PM, Viresh Kumar wrote:
> External email: Use caution opening links or attachments
> 
> 
> On 22-06-20, 03:04, 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.
> 
> You shouldn't be putting how linux is going to use this information and entries
> shouldn't be made just so cpufreq can bind to a driver.
> 
> Though I see that this is a real hardware register which you can use to interact
> with the firmware ? And so it makes sense to have it, maybe in different form
> though.
> 
CPUFREQ driver doesn't communicate directly with BPMP firmware. It uses 
BPMP node's reference to call api's exported by BPMP driver which 
communicates with BPMP firmware.

> I will let Rob explain what would be the right way of doing this though.
> 
This is already discussed by Thierry with Rob.
Please refer https://marc.info/?l=linux-arm-kernel&m=158999171528418&w=2

>>
>> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
>> ---
>>   Documentation/devicetree/bindings/arm/cpus.yaml | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml
>> index a018147..737b55e 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
>>         - qcom,krait
>>         - qcom,kryo
>>         - qcom,kryo260
>> @@ -255,6 +256,14 @@ properties:
>>
>>         where voltage is in V, frequency is in MHz.
>>
>> +  nvidia,bpmp:
>> +    $ref: '/schemas/types.yaml#/definitions/phandle'
>> +    descrption: |
>> +      Specifies the bpmp node that needs to be queried to get
>> +      operating point data for all CPUs.
>> +
>> +      Optional for NVIDIA Tegra194 Carmel CPUs
>> +
>>     power-domains:
>>       $ref: '/schemas/types.yaml#/definitions/phandle-array'
>>       description:
>> --
>> 2.7.4
> 
> --
> viresh
>
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml
index a018147..737b55e 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
       - qcom,krait
       - qcom,kryo
       - qcom,kryo260
@@ -255,6 +256,14 @@  properties:
 
       where voltage is in V, frequency is in MHz.
 
+  nvidia,bpmp:
+    $ref: '/schemas/types.yaml#/definitions/phandle'
+    descrption: |
+      Specifies the bpmp node that needs to be queried to get
+      operating point data for all CPUs.
+
+      Optional for NVIDIA Tegra194 Carmel CPUs
+
   power-domains:
     $ref: '/schemas/types.yaml#/definitions/phandle-array'
     description: