Re: [PATCH v4 0/4] Enable ICE clock scaling

[Konrad Dybcio]

On 2/2/26 7:36 AM, Abhinaba Rakshit wrote:
> On Thu, Jan 29, 2026 at 01:17:51PM +0100, Konrad Dybcio wrote:
>> On 1/28/26 9:46 AM, Abhinaba Rakshit wrote:
>>> Introduce support for dynamic clock scaling of the ICE (Inline Crypto Engine)
>>> using the OPP framework. During ICE device probe, the driver now attempts to
>>> parse an optional OPP table from the ICE-specific device tree node to
>>> determine minimum and maximum supported frequencies for DVFS-aware operations.
>>> API qcom_ice_scale_clk is exposed by ICE driver and is invoked by UFS host
>>> controller driver in response to clock scaling requests, ensuring coordination
>>> between ICE and host controller.
>>>
>>> For MMC controllers that do not support clock scaling, the ICE clock frequency
>>> is kept aligned with the MMC controller’s clock rate (TURBO) to ensure
>>> consistent operation.
>>
>> You skipped that bit, so I had to do a little digging..
>>
>> This paragraph sounds scary on the surface, as leaving a TURBO vote hanging
>> would absolutely wreck the power/thermal profile of a running device,
>> however sdhci-msm's autosuspend functions quiesce the ICE by calling
>> qcom_ice_suspend()
>>
>> I think you're missing a dev_pm_opp_set(dev, NULL) or so in that function
>> and a mirrored restore in _resume
> 
> Thanks for pointing this out, its an important piece which is missed.
> We can use dev_pm_opp_set_rate(dev, 0/min_freq) in _suspend and restore the

FWIW

dev_pm_opp_set_rate(0) will drop the rpmh vote altogether and NOT
disable the clock or change its rate

dev_pm_opp_set_rate(min_freq) will *lower* the rpmh vote and DO
set_rate (the clock is also left on)

Konrad

> suspended frequency in the _resume. Something similar which is used by sdhci-msm.