On 19-08-19, 14:39, Viresh Kumar wrote:
> On 09-08-19, 17:58, Sylwester Nawrocki wrote:
> > Thank you for your suggestions.
> >
> > For some Exynos SoC variants the algorithm of selecting CPU voltage supply
> > is a bit more complex than just selecting a column in the frequency/voltage
> > matrix, i.e. selecting a set of voltage values for whole frequency range.
> >
> > Frequency range could be divided into sub-ranges and to each such a sub-range
> > part of different column could be assigned, depending on data fused in
> > the CHIPID block registers.
> >
> > We could create OPP node for each frequency and specify all needed voltages
> > as a list of "opp-microvolt-<name>" properties but apart from the fact that
> > it would have been quite many properties, e.g. 42 (3 tables * 14 columns),
> > only for some SoC types the dev_pm_opp_set_prop_name() approach could be
> > used. We would need to be able to set opp-microvolt-* property name
> > separately for each frequency (OPP).
> >
> > Probably most future proof would be a DT binding where we could still
> > re-create those Exynos-specific ASV tables from DT. For example add named
> > opp-microvolt-* properties or something similar to hold rows of each ASV
> > table. But that conflicts with "operating-points-v2" binding, where
> > multiple OPP voltage values are described by just named properties and
> > multiple entries correspond to min/target/max.
> >
> > opp_table0 {
> > compatible = "...", "operating-points-v2";
> > opp-shared;
> > opp-2100000000 {
> > opp-hz = /bits/ 64 <1800000000>;
> > opp-microvolt = <...>;
> > opp-microvolt-t1 = <1362500>, <1350000>, ....;
> > opp-microvolt-t2 = <1362500>, <1360000>, ....;
> > opp-microvolt-t3 = <1362500>, <1340000>, ....;
> > };
> > ...
> > opp-200000000 {
> > opp-hz = /bits/ 64 <200000000>;
> > opp-microvolt = <...>;
> > opp-microvolt-t1 = <900000>, <900000>, ....;
> > opp-microvolt-t2 = <900000>, <900000>, ....;
> > opp-microvolt-t3 = <900000>, <900000>, ....;
> > };
> > };
> >
> > I might be missing some information now on how those Exynos ASV tables
> > are used on other SoCs that would need to be supported.
> >
> > There will be even more data to include when adding support for the Body
> > Bias voltage, for each CPU supply voltage we could possibly have
> > corresponding Body Bias voltage.
>
> Will something like this help ?
>
> https://lore.kernel.org/lkml/1442623929-4507-3-git-send-email-sboyd@xxxxxxxxxxxxxx/
>
> This never got merged but the idea was AVS only.
Here is a recent version under review.
https://lore.kernel.org/lkml/1565703113-31479-1-git-send-email-andrew-sh.cheng@xxxxxxxxxxxx
--
viresh
