Re: [PATCH v3 20/24] pmdomain: core: Default to use of_genpd_sync_state() for genpd providers

[Jon Hunter]

Hi Ulf,

On 11/08/2025 13:11, Ulf Hansson wrote:
> On Thu, 31 Jul 2025 at 17:07, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
> > Hi Ulf,
> >
> > On 01/07/2025 12:47, Ulf Hansson wrote:
> > > Unless the typical platform driver that act as genpd provider, has its own
> > > ->sync_state() callback implemented let's default to use
> > > of_genpd_sync_state().
> > >
> > > More precisely, while adding a genpd OF provider let's assign the
> > > ->sync_state() callback, in case the fwnode has a device and its driver
> > > doesn't have the ->sync_state() set already. In this way the typical
> > > platform driver doesn't need to assign ->sync_state(), unless it has some
> > > additional things to manage beyond genpds.
> > >
> > > Suggested-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> > > Tested-by: Hiago De Franco <hiago.franco@xxxxxxxxxxx> # Colibri iMX8X
> > > Tested-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> # TI AM62A,Xilinx ZynqMP ZCU106
> > > Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> > > ---
> > >    drivers/pmdomain/core.c | 9 +++++++++
> > >    1 file changed, 9 insertions(+)
> > >
> > > diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> > > index ca47f91b9e91..5cef6de60c72 100644
> > > --- a/drivers/pmdomain/core.c
> > > +++ b/drivers/pmdomain/core.c
> > > @@ -2600,6 +2600,11 @@ static bool genpd_present(const struct generic_pm_domain *genpd)
> > >        return ret;
> > >    }
> > >
> > > +static void genpd_sync_state(struct device *dev)
> > > +{
> > > +     return of_genpd_sync_state(dev->of_node);
> > > +}
> > > +
> > >    /**
> > >     * of_genpd_add_provider_simple() - Register a simple PM domain provider
> > >     * @np: Device node pointer associated with the PM domain provider.
> > > @@ -2628,6 +2633,8 @@ int of_genpd_add_provider_simple(struct device_node *np,
> > >        if (!dev && !genpd_is_no_sync_state(genpd)) {
> > >                genpd->sync_state = GENPD_SYNC_STATE_SIMPLE;
> > >                device_set_node(&genpd->dev, fwnode);
> > > +     } else {
> > > +             dev_set_drv_sync_state(dev, genpd_sync_state);
> > >        }
> > >
> > >        put_device(dev);
> > > @@ -2700,6 +2707,8 @@ int of_genpd_add_provider_onecell(struct device_node *np,
> > >        dev = get_dev_from_fwnode(fwnode);
> > >        if (!dev)
> > >                sync_state = true;
> > > +     else
> > > +             dev_set_drv_sync_state(dev, genpd_sync_state);
> > >
> > >        put_device(dev);
> >
> > Following this change I am seeing the following warning on our Tegra194
> > devices ...
> >
> >    WARNING KERN tegra-bpmp bpmp: sync_state() pending due to 17000000.gpu
> >    WARNING KERN tegra-bpmp bpmp: sync_state() pending due to 3960000.cec
> >    WARNING KERN tegra-bpmp bpmp: sync_state() pending due to 15380000.nvjpg
> >    WARNING KERN tegra-bpmp bpmp: sync_state() pending due to 154c0000.nvenc
> >    WARNING KERN tegra-bpmp bpmp: sync_state() pending due to 15a80000.nvenc
> >
> > Per your change [0], the 'GENPD_FLAG_NO_SYNC_STATE' is set for Tegra
> > and so should Tegra be using of_genpd_sync_state() by default?
>
> This is a different power-domain provider (bpmp) in
> drivers/firmware/tegra/bpmp.c and
> drivers/pmdomain/tegra/powergate-bpmp.c.
>
> For the bpmp we don't need GENPD_FLAG_NO_SYNC_STATE, as the
> power-domain provider is described along with the
> "nvidia,tegra186-bpmp" compatible string. In the other case
> (drivers/soc/tegra/pmc.c) the "core-domain" and "powergates" are
> described through child-nodes, while ->sync_state() is managed by the
> parent-device-node.
>
> In the bpmp case there is no ->sync_state() callback assigned, which
> means genpd decides to assign a default one.
>
> The reason for the warnings above is because we are still waiting for
> those devices to be probed, hence the ->sync_state() callback is still
> waiting to be invoked. Enforcing ->sync_state() callback to be invoked
> can be done via user-space if that is needed.
>
> Did that make sense?

Sorry for the delay, I was on vacation. Yes makes sense and drivers for 
some of the above drivers are not yet upstreamed to mainline and so this 
would be expected for now.

Thanks
Jon

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