Hi Rob, On Tue, Feb 28, 2017 at 4:52 PM, Rob Herring <r...@kernel.org> wrote: > On Tue, Feb 28, 2017 at 9:14 AM, Ulf Hansson <ulf.hans...@linaro.org> wrote: >> [...] >> >>>> ---> Parent domain-2 (Contains >>>> Perfomance states) >>>> | >>>> | >>>> C.) DeviceX ---> Parent-domain-1 | >>>> | >>>> | >>>> ---> Parent domain-3 (Contains >>>> Perfomance states) >>> >>> I'm a bit confused. How does a domain have 2 parent domains? >> >> This comes from the early design of the generic PM domain, thus I >> assume we have some HW with such complex PM topology. However, I don't >> know if it is actually being used. >> >> Moreover, the corresponding DT bindings for "power-domains" parents, >> can easily be extended to cover more than one parent. See more in >> Documentation/devicetree/bindings/power/power_domain.txt > > I could easily see device having 2 power domains. For example a cpu > may have separate domains for RAM/caches and logic. And nesting of > power domains is certainly common, but a power domain being contained > in 2 different parents? I don't even see how that is possible in the > physical design. Now if we're mixing PM and power domains again and > the cpu device is pointing to the cpu PM domain which contains 2 power > domains, then certainly that is possible.
One of them could be a power area, the other a clock domain. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org 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