Hi Matt,
On Fri, 23 Jan 2026 at 14:36, Matt Coster <[email protected]> wrote:
> On 22/01/2026 16:08, Geert Uytterhoeven wrote:
> > Call the dev_pm_domain_attach_list() and dev_pm_domain_detach_list()
> > helpers instead of open-coding multi PM Domain handling.
> >
> > This changes behavior slightly:
> > - The new handling is also applied in case of a single PM Domain,
> > - PM Domains are now referred to by index instead of by name, but
> > "make dtbs_check" enforces the actual naming and ordering anyway,
> > - There are no longer device links created between virtual domain
> > devices, only between virtual devices and the parent device.
>
> We still need this guarantee, both at start and end of day. In the
> current implementation dev_pm_domain_attach_list() iterates forwards,
> but so does dev_pm_domain_detach_list(). Even if we changed that, I'd
> prefer not to rely on the implementation details when we can declare the
> dependencies explicitly.
Note that on R-Car, the PM Domains are nested (see e.g. r8a7795_areas[]),
so they are always (un)powered in the correct order. But that may not
be the case in the integration on other SoCs.
> We had/have a patch (attached) kicking around internally to use the
> *_list() functions but keep the inter-domain links in place; it got held
> up by discussions as to whether we actually need those dependencies for
> the hardware to behave correctly. Your patch spurred me to run around
> the office and nag people a bit, and it seems we really do need to care
> about the ordering.
OK.
> Can you add the links back in for a V2 or I can properly send the
> attached patch instead, I don't mind either way.
Please move forward with your patch, you are the expert.
I prefer not to be blamed for any breakage ;-)
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
