Re: [PATCH 4/7] serial: qcom-geni: Use geni_se_set_rate() for source clock configuration

[Konrad Dybcio]

On 8/25/26 6:00 AM, Praveen Talari wrote:
> HI Konrad,
> 
> On 24-08-2026 20:35, Konrad Dybcio wrote:
>> On 8/4/26 9:57 PM, Praveen Talari wrote:
>>> The driver calls dev_pm_opp_set_rate() directly on uport->dev to apply
>>> the computed source clock frequency, and dispatches baud rate handling
>>> through a per-variant dev_data->set_rate() callback that either
>>> recalculates the clock divider (Linux clock managed path) or selects
>>> a performance level via geni_se_set_perf_level() (SA8255P firmware
>>> managed path).
>> [...]
>>
>>> +    geni_se_set_rate(&port->se, 0);
>> This ends up calling dev_pm_opp_set_rate(0) [i see this is an existing
>> bug in geni_se_resources_deactivate()], which removes the power vote,
>> but does nothing to the clock (neither set_rate nor disable_unprepare),
>> which will crash the platform
>>
>> Both of these calls (new and existing) should be removed. Clocks will
>> be disabled by geni_se_clks_off() in geni_se_resources_deactivate().
>>
>> Then, we should do dev_pm_set_opp(se->dev, NULL) *after* they are off
>> to remove any trailing OPP resources (i.e. icc votes defined in the OPP
>> table in our case)
> So, if I understand correctly, the expected sequence is:
> 
> 1. Disable the clocks.
> 
> 2. Remove the OPP/performance resources.

Yes, otherwise there is no guarantee that the clocks have sufficient
power for a given rate

Konrad