Re: [PATCH v5 2/4] soc: qcom: ice: Add OPP-based clock scaling support for ICE

[Konrad Dybcio]

On 2/18/26 8:02 PM, Abhinaba Rakshit wrote:
> On Mon, Feb 16, 2026 at 01:18:57PM +0100, Konrad Dybcio wrote:
>> On 2/13/26 8:02 AM, Abhinaba Rakshit wrote:
>>> On Thu, Feb 12, 2026 at 12:30:00PM +0100, Konrad Dybcio wrote:
>>>> On 2/11/26 10:47 AM, Abhinaba Rakshit wrote:
>>>>> Register optional operation-points-v2 table for ICE device
>>>>> and aquire its minimum and maximum frequency during ICE
>>>>> device probe.

[...]

>>> However, my main concern was for the corner cases, where:
>>> (target_freq > max && ROUND_CEIL)
>>> and
>>> (target_freq < min && ROUND_FLOOR)
>>> In both the cases, the OPP APIs will fail and the clock remains unchanged.
>>
>> I would argue that's expected behavior, if the requested rate can not
>> be achieved, the "set_rate"-like function should fail
>>
>>> Hence, I added the checks to make the API as generic/robust as possible.
>>
>> AFAICT we generally set storage_ctrl_rate == ice_clk_rate with some slight
>> play, but the latter never goes above the FMAX of the former
>>
>> For the second case, I'm not sure it's valid. For "find lowest rate" I would
>> expect find_freq_*ceil*(rate=0). For other cases of scale-down I would expect
>> that we want to keep the clock at >= (or ideally == )storage_ctrl_clk anyway
>> so I'm not sure _floor() is useful
> 
> Clear, I guess, the idea is to ensure ice-clk <= storage-clk in case of scale_up
> and ice-clk >= storage-clk in case of scale_down.

I don't quite understand the first case (ice <= storage for scale_up), could you
please elaborate?

Konrad