Re: [PATCH v1 1/4] dt-bindings: Add CIX Sky1 USB bindings

[Krzysztof Kozlowski <krzk@kernel.org>]

On 02/09/2026 05:23, Hongliang Yang wrote:
> 
>>> +  reg:
>>> +    items:
>>> +      - description: AXI property configuration register
>>> +      - description: Controller status register
>>
>> Registers are not address spaces. Devices do not have address spaces of
>> one register, so this is not a real device.
> 
> I understand the concern, and we looked at this again against the SoC
> documentation. These two registers are RCSU (system configuration
> unit) registers, but each of them is dedicated to one USB controller
> and not shared with any other device:
> 
>  - The first register is the controller's Control Register for the AXI
>    cache attributes. Its bit fields are awcache[3:0] (bits 3:0) and
>    arcache[3:0] (bits 7:4), i.e. the AXI cache attributes of the
>    controller's own AXI master interface. The glue driver programs it
>    once during initialization.
> 
>  - The second register is a status register providing the AXI clock
>    valid status the driver polls while enabling the controller.
> 
> The two instances submitted in this series illustrate the per-device
> offsets: the USB4 controller uses 0x091c0314 (AXI cache attributes)
> and 0x091c0400 (status), while USB5 uses 0x091c0324 and 0x091c0410.

You need to describe the address ranges, hierarchy, not the registers.


Best regards,
Krzysztof

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