Re: [PATCH 00/11] pmdomain: Add generic ->sync_state() support to genpd

Saravana Kannan
2025-04-18T00:54:15Z

On Thu, Apr 17, 2025 at 7:25 AM Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> If a PM domain (genpd) is powered-on during boot, there is probably a good
> reason for it. Therefore it's known to be a bad idea to allow such genpd to be
> powered-off before all of its consumer devices have been probed. This series
> intends to fix this problem.
>
> We have been discussing these issues at LKML and at various Linux-conferences
> in the past. I have therefore tried to include the people I can recall being
> involved, but I may have forgotten some (my apologies), feel free to loop them
> in.
>
> A few notes:
> *)
> Even if this looks good, the last patch can't go in without some additional
> changes to a couple of existing genpd provider drivers. Typically genpd provider
> drivers that implements ->sync_state() need to call of_genpd_sync_state(), but I
> will fix this asap, if we think the series makes sense.
>
> *)
> Patch 1 -> 3 are just preparatory cleanups.
>
> *)
> I have tested this with QEMU with a bunch of local test-drivers and DT nodes.
> Let me know if you want me to share this code too.
>
>
> Please help review and test!
> Finally, a big thanks to Saravana for all the support!

You are welcome! Thank you for getting this series done! Happy to see
sync_state() support being added to another framework.

I skimmed the series and at a high level it looks right. Not too
familiar with power domain code, so I didn't go deep. Just reviewed
the fw_devlink and driver core parts of it.

-Saravana

>
> Kind regards
> Ulf Hansson
>
>
> Saravana Kannan (1):
> driver core: Add dev_set_drv_sync_state()
>
> Ulf Hansson (10):
> pmdomain: core: Convert genpd_power_off() to void
> pmdomain: core: Simplify return statement in genpd_power_off()
> pmdomain: core: Use genpd->opp_table to simplify error/remove path
> pmdomain: core: Add a bus and a driver for genpd providers
> pmdomain: core: Use device_set_node() to assign the fwnode too
> pmdomain: core: Add the genpd->dev to the genpd provider bus
> pmdomain: core: Export a common ->sync_state() helper for genpd
> providers
> pmdomain: core: Add internal ->sync_state() support for genpd
> providers
> pmdomain: core: Default to use of_genpd_sync_state() for genpd
> providers
> pmdomain: core: Leave powered-on genpds on until ->sync_state()
>
> drivers/pmdomain/core.c | 273 +++++++++++++++++++++++++++++++-------
> include/linux/device.h | 12 ++
> include/linux/pm_domain.h | 11 ++
> 3 files changed, 249 insertions(+), 47 deletions(-)
>
> --
> 2.43.0
>