[PATCH v2 0/9] driver core / pmdomain: Add support for fined grained sync_state

[Ulf Hansson <ulf.hansson@linaro.org>]

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.

Note that, onecell power domain providers are very common. It's being used by
many SoCs/platforms/technologies. To name a few:
SCMI, Qualcomm, NXP, Mediatek, Renesas, TI, etc.

Anyway, 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 and help review/test!

Kind regards
Ulf Hansson

[1]
https://lore.kernel.org/all/20250701114733.636510-1-ulf.hansson@linaro.org/

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                   | 205 ++++++++++++++++++----
 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, 197 insertions(+), 42 deletions(-)

-- 
2.43.0