[PATCH v3 00/24] pmdomain: Add generic ->sync_state() support to genpd

[Ulf Hansson]

On Wed, 3 Sept 2025 at 09:39, Sebin Francis <sebin.francis at ti.com> wrote:
>
> Hi Ulf,
>
> On 01/07/25 17:17, Ulf Hansson wrote:
> > Changes in v3:
> >       - Added a couple of patches to adress problems on some Renesas
> >       platforms. Thanks Geert and Tomi for helping out!
> >       - Adressed a few comments from Saravanna and Konrad.
> >       - Added some tested-by tags.
> >
> > Changes in v2:
> >       - Well, quite a lot as I discovered various problems when doing
> >       additional testing of corner-case. I suggest re-review from scratch,
> >       even if I decided to keep some reviewed-by tags.
> >       - Added patches to allow some drivers that needs to align or opt-out
> >       from the new common behaviour in genpd.
> >
> > 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.
> > > 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!
>
> During testing on a TI platform, I observed new kernel warnings after
> applying this patch series:
>
> ti_sci_pm_domains 44043000.system-controller:power-controller:
> sync_state() pending due to fd00000.gpu
>
> These warnings occur when a device (in this case, the GPU) has no driver
> bound to it. The fw_devlink_dev_sync_state[0] in the core has a check
> before printing this warning. It checks whether the device driver has a
> sync_state handler OR the device bus has a sync_state handler in the
> dev_has_sync_state[1]. If both conditions are false,
> fw_devlink_dev_sync_state[0] performs an early return before printing
> the warning.
>
> Before this patch series, both handlers were absent for device driver
> ti_sci_pm_domains and the device bus, so both conditions failed and no
> warnings were printed.
>
> This patch series adds a sync_state handler for the bus, which now
> satisfies the second condition. So it doesn't do an early return and
> proceeds to print the warning.

Thanks for the report and testing!

Indeed this is the new and expected behaviour. I agree that it's
certainly questionable if those prints should be at the warning level.

We should probably downgrade those to dev_info(), at least. Let me
send a patch to see what Saravana and others are thinking about it!

>
> [0]: https://elixir.bootlin.com/linux/v6.16/source/drivers/base/core.c#L1777
> [1]:
> https://elixir.bootlin.com/linux/v6.16/source/include/linux/device.h#L909
>
> Thanks
> Sebin

[...]

Kind regards
Uffe