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.
--
viresh
