On Tue, Oct 8, 2024 at 11:14 AM Geert Uytterhoeven <geert+renesas@xxxxxxxxx> wrote: > When CONFIG_ENERGY_MODEL=y, an error is printed on RZ/G2E and R-Car E3: > > cpu cpu0: EM: invalid perf. state: -22 > > This happens because the Operating Points Parameters tables do not list > voltages, as they are all identical. Previously, it was assumed they > were optional, and unused, when none of the CPU nodes is tied to a > regulator using the "cpu-supply" property. This assumption turned out > to be incorrect, causing the reported error message. > > This RFC patch series fixes this by adding the missing voltages. > > Note that the Energy Model calculates energy efficiency by dividing the > (estimated) CPU power consumption by CPU core clock frequency. When all > voltages have the same value, the former is proportional to clock > frequency, and energy efficiency becomes a constant. Hence all > operating points are considered to have the same efficiency, and the > Energy Model always picks the one with the highest clock rate (see also > [1]). > > Alternatively, the Energy Model could be changed to silently ignore OPP > tables with missing frequencies. IMHO this is not an unusual case. > > Which approach should be taken? > Thanks for your comments! Any comments from the Energy Model and PM people? Thanks! > [1] "PM: EM: Question Potential Issue with EM and OPP Table in cpufreq > ondemand Governor" > https://lore.kernel.org/all/a2ca883e-122e-43a1-b377-c43956b5b3be@xxxxxxx > > Geert Uytterhoeven (2): > arm64: dts: renesas: r8a774c0: Re-add voltages to OPP table > arm64: dts: renesas: r8a77990: Re-add voltages to OPP table Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
