Re: [PATCH V3 11/15] cpufreq: mediatek: Link CCI device to CPU

[Kevin Hilman]

Hi Rex,

Rex-BC Chen <rex-bc.chen@xxxxxxxxxxxx> writes:

> From: Jia-Wei Chang <jia-wei.chang@xxxxxxxxxxxx>
>
> In some MediaTek SoCs, like MT8183, CPU and CCI share the same power
> supplies. Cpufreq needs to check if CCI devfreq exists and wait until
> CCI devfreq ready before scaling frequency.
>
> Before CCI devfreq is ready, we record the voltage when booting to
> kernel and use the max(cpu target voltage, booting voltage) to
> prevent cpufreq adjust to the lower voltage which will cause the CCI
> crash because of high frequency and low voltage.
>
> - Add is_ccifreq_ready() to link CCI device to CPI, and CPU will start
>   DVFS when CCI is ready.
> - Add platform data for MT8183.
>
> Signed-off-by: Jia-Wei Chang <jia-wei.chang@xxxxxxxxxxxx>
> Signed-off-by: Rex-BC Chen <rex-bc.chen@xxxxxxxxxxxx>

The solution of keeping the max of the CPU voltage from OPP and boot-up
voltage makes sense until CCI is ready.  Thank you for the rework and
the detailed technical explanations.

Reviewed-by: Kevin Hilman <khilman@xxxxxxxxxxxx>

Kevin