Re: [PATCH v5 4/4] ARM: dts: qcom: ipq8064: Add CPU OPP table

[Konrad Dybcio]

On 10/10/23 22:00, Christian Marangi wrote:
> On Tue, Oct 10, 2023 at 09:52:50PM +0200, Konrad Dybcio wrote:
> > On 10/10/23 16:15, Christian Marangi wrote:
> > > On Tue, Oct 10, 2023 at 03:40:32PM +0200, Konrad Dybcio wrote:
> > > > On 9/30/23 12:21, Robert Marko wrote:
> > > > > From: Christian Marangi <ansuelsmth@xxxxxxxxx>
> > > > >
> > > > > Add CPU OPP table for IPQ8062, IPQ8064 and IPQ8065 SoC.
> > > > > Use opp-supported-hw binding to correctly enable and disable the
> > > > > frequency as IPQ8062 supports up to 1.0Ghz, IPQ8064 supports up to
> > > > > 1.4GHz with 1.2GHz as an additional frequency and IPQ8065 supports
> > > > > 1.7GHZ but doesn't have 1.2GHZ frequency and has to be disabled.
> > > > >
> > > > > Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
> > > > > Signed-off-by: Robert Marko <robimarko@xxxxxxxxx>
> > > > > ---
> > > > Christian/Robert, can you provide a downstream source for this?
> > >
> > > Sure, consider that everything is with +/-5%.
> > Hm, so you're e.g. putting ipq8062 384MHz voltage for PVS3 equal to
> > 0.95*800000 = 760000, but I'm not sure if it's a good idea?
> >
> > The comment in downstream:
> >
> > "These are based on +/-5% Margin on the VDD_APCx that is advertised in our
> > Datasheet across Temperature"
> >
> > suggests this is already not very accurate, and betting that the lower
> > threshold works on all chips is probably not the best idea.
>
> Consider that everything is driven by the rpm. The original qsdk used the
> same approach of taking the value, apply +-5% and pass it as a voltage
> triplet to the rpm regulator. Also the driver have ranges so it
> autodecide the best voltage in the range of the voltage triplet based on
> the one supported by the regulator. Normally the normal voltage is
> always used.
Eeh? So you pass any half-random value to it and RPM edits it in flight?

Please be more specific, I'm not very familiar with this platform

Konrad