Re: [PATCH 1/6] dt-bindings: loongarch: Add CPU bindings for LoongArch

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On 17/06/2023 08:31, Binbin Zhou wrote:
> On Fri, Jun 16, 2023 at 5:51 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@xxxxxxxxxx> wrote:
>>
>> On 16/06/2023 08:10, Binbin Zhou wrote:
>>> Add the available CPUs in LoongArch binding with DT schema format using
>>> json-schema.
>>>
>>> Signed-off-by: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
>>> ---
>>>  .../devicetree/bindings/loongarch/cpus.yaml   | 65 +++++++++++++++++++
>>>  1 file changed, 65 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/loongarch/cpus.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/loongarch/cpus.yaml b/Documentation/devicetree/bindings/loongarch/cpus.yaml
>>> new file mode 100644
>>> index 000000000000..c3e2dba42c81
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/loongarch/cpus.yaml
>>> @@ -0,0 +1,65 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/loongarch/cpus.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: LoongArch CPUs
>>> +
>>> +maintainers:
>>> +  - Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
>>> +
>>> +description:
>>> +  The device tree allows to describe the layout of CPUs in a system through
>>> +  the "cpus" node, which in turn contains a number of subnodes (ie "cpu")
>>> +  defining properties for every CPU.
>>
>> I understand you copied it from ARM, but I would prefer to have here
>> something meaningful. Bindings description does not explain what is DTS,
>> but explains what the hardware is.
> 
> Hi Krzysztof:
> 
> I am very sorry, this is my problem and I will rewrite this part.
> 
>>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - loongson,la264
>>> +      - loongson,la364
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  device_type: true
>>> +
>>> +  clock-frequency:
>>> +    description: The frequency of cpu in Hz.
>>> +
>>> +  model:
>>> +    $ref: /schemas/types.yaml#/definitions/string
>>> +    description: User-visible cpu name in /proc/cpuinfo.
>>
>> First, aren't you mixing nodes?
>> Second, it is derived from compatible, so no need for such property.
> 
> Well, this attribute is an attempt to tweak it.
> 
> As the description says, this attribute was added to show the model
> name in /proc/cpuinfo. here, we will show the custom name instead of
> using the cpu core name directly.

DTS is not some translation layer. You can decode compatible and put
into /proc/cpuinfo whatever you wish.

> 
> For example, on a Loongson-3A5000 machine, although its cpu core is
> la464, we can see:
> [root@fedora ~]# cat /proc/cpuinfo
> system type : generic-loongson-machine
> ..............
> Model Name : Loongson-3A5000-HV
> ............
> CPU MHz : 2500.00
> ...........
> 
> Unfortunately, some Loongson-2K chips are not designed with
> corresponding CPUNAME registers, so we expect to add them in the DTS.
> 
> At first, we considered writing it directly into cpu compatible, but
> it seems that dts compatible is all lower case, while our desired
> model name contains upper case letters.
> 
> What do you think if we repositioned this attribute under cpu?

You already did it, so about which solution we talk about?

Anyway, I am against store translation of compatibles in DTS.

Best regards,
Krzysztof




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