Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 18-10-19, 17:03, andrew-sh.cheng wrote:
> On Thu, 2019-10-17 at 12:01 +0530, Viresh Kumar wrote:
> > On 16-10-19, 10:43, andrew-sh.cheng wrote:
> > > This is due to SVS feature need to fix Vproc for calibration.
> > > When SVS calibration, it want to disable all opp items, except one with
> > > voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> > > corresponding voltage is not 1.0V)
> > > In this way, SVS can make sure there is no other module, include
> > > thermal, will change Vproc by DVFS driver.
> > > After SVS calibration done, SVS will enable those disabled opp items
> > > back.
> > 
> > But why is this required to be done this way ? Why can't we just update the
> > voltages without doing this disable/enable dance ?
> > 
> This is because some opp items need voltage larger than 1.0V.
> We cannot update the voltage to 1.0V.
> 
> If we don't disable these opp items, and DVFS policy want to set these
> high frequencies, dvfs driver will set higher voltage to Vproc and SVS
> calibration will be fail.

Okay.

-- 
viresh