Re: [PATCH 0/9] driver core / pmdomain: Add support for fined grained sync_state

[Saravana Kannan]

On Thu, Mar 19, 2026 at 9:59 AM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
> On Tue, 3 Mar 2026 at 14:23, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> >
> > Since the introduction [1] of the common sync_state support for pmdomains
> > (genpd), we have encountered a lot of various interesting problems. In most
> > cases the new behaviour of genpd triggered some weird platform specific bugs.
> >
> > That said, in LPC in Tokyo me and Saravana hosted a session to walk through the
> > remaining limitations that we have found for genpd's sync state support. In
> > particular, we discussed the problems we have for the so-called onecell power
> > domain providers, where a single provider typically provides multiple
> > independent power domains, all with their own set of consumers.
> >
> > In these cases, the generic sync_state mechanism with fw_devlink isn't fine
> > grained enough, as we end up waiting for all consumers for all power domains
> > before the ->sync_callback gets called for the supplier/provider. In other
> > words, we may end up keeping unused power domains powered-on, for no good
> > reasons.
> >
> > The series intends to fix this problem. Please have a look at the commit
> > messages for more details.
> >
> > Please help review and test!
>
> Saravana, Rafael, Greg - any concerns you see with this approach?

Not specifically related to this thread, but a general update so
people know I haven't vanished. I've been reading this and all the
other fw_devlink related patches (Doug's making flags set/clear/check
safe, overlay series, the PCIe patch series, etc) being sent since I
last replied. I somehow missed this one. I'll definitely take a look
at this series.

Email replies to LKML are a pain right now but it's
expected to get much easier in a week or two. I'm holding off on
responding to most emails until then.

Thanks,
Saravana

>
> Especially I need your confirmation for patch 1 and patch2.
>
> Kind regards
> Uffe
>
>
> >
> > Kind regards
> > Ulf Hansson
> >
> > [1]
> > https://lore.kernel.org/all/20250701114733.636510-1-ulf.hansson@xxxxxxxxxx/
> >
> >
> > Ulf Hansson (9):
> >   driver core: Enable suppliers to implement fine grained sync_state
> >     support
> >   driver core: Add dev_set_drv_queue_sync_state()
> >   pmdomain: core: Move genpd_get_from_provider()
> >   pmdomain: core: Add initial fine grained sync_state support
> >   pmdomain: core: Extend fine grained sync_state to more onecell
> >     providers
> >   pmdomain: core: Export a common function for ->queue_sync_state()
> >   pmdomain: renesas: rcar-gen4-sysc: Drop GENPD_FLAG_NO_STAY_ON
> >   pmdomain: renesas: rcar-sysc: Drop GENPD_FLAG_NO_STAY_ON
> >   pmdomain: renesas: rmobile-sysc: Drop GENPD_FLAG_NO_STAY_ON
> >
> >  drivers/base/core.c                       |   7 +-
> >  drivers/pmdomain/core.c                   | 208 ++++++++++++++++++----
> >  drivers/pmdomain/renesas/rcar-gen4-sysc.c |   1 -
> >  drivers/pmdomain/renesas/rcar-sysc.c      |   1 -
> >  drivers/pmdomain/renesas/rmobile-sysc.c   |   3 +-
> >  include/linux/device.h                    |  12 ++
> >  include/linux/device/driver.h             |   7 +
> >  include/linux/pm_domain.h                 |   3 +
> >  8 files changed, 200 insertions(+), 42 deletions(-)
> >
> > --
> > 2.43.0
> >