Re: [PATCH 1/3] dt-bindings: interconnect: add clocks property to enable QoS on sa8775p

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 8/28/25 11:59 PM, Georgi Djakov wrote:
> On 8/28/25 9:20 PM, Krzysztof Kozlowski wrote:
>> On 28/08/2025 20:16, Odelu Kukatla wrote:
>>>
>>>>> QoS configuration is essential for managing latency and bandwidth across
>>>>> subsystems such as CPU, GPU, and multimedia engines. Without it, the
>>>>> system may experience performance degradation, especially under
>>>>
>>>> So how was it working for the last 2 years?
>>>>
>>> The system may function normally without this feature. However, enabling
>>
>>
>> Huh? So you agree but keep continuing the discussion?
>>
>> I don't understand what we are discussing in such case, but just to
>> close the topic from my side and be explicit: based on above you cannot
>> break the ABI.
> 
> To be even more specific, if we already have some DT binding without any
> clocks and reg properties, we can't just suddenly change them from now
> on to be "required". But they can still be "optional" and this will not
> break the ABI, right? The old DT is still valid and the QoS will be
> active when the new properties are present and this is handled properly
> by the driver.

Correct and this very approach was used to retrofit QoS onto an even older
sc7280 icc driver.

The icc-rpmh core already ignores QoS configuration if the clocks are not
provided.

Konrad