Re: [RFC 0/3] Introduce cpufreq minimum load QoS

[Benjamin GAIGNARD]

On 4/29/20 5:50 PM, Rafael J. Wysocki wrote:
> On Friday, April 24, 2020 1:40:55 PM CEST Benjamin Gaignard wrote:
>> When start streaming from the sensor the CPU load could remain very low
>> because almost all the capture pipeline is done in hardware (i.e. without
>> using the CPU) and let believe to cpufreq governor that it could use lower
>> frequencies. If the governor decides to use a too low frequency that
>> becomes a problem when we need to acknowledge the interrupt during the
>> blanking time.
>> The delay to ack the interrupt and perform all the other actions before
>> the next frame is very short and doesn't allow to the cpufreq governor to
>> provide the required burst of power. That led to drop the half of the frames.
>>
>> To avoid this problem, DCMI driver informs the cpufreq governors by adding
>> a cpufreq minimum load QoS resquest.
> This seems to be addressing a use case that can be addressed with the help of
> utilization clamps with less power overhead.
Do mean clamping the policy frequencies ? I may have miss the API to do 
that...
>
> Thanks!
>
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