Re: [PATCH 1/2] pmdomain: imx8mp-blk-ctrl: set awake path for power_dev if attached device needs wakeup

On Wed, 4 Feb 2026 at 09:48, Xu Yang [off-list ref] wrote:

On Tue, Feb 03, 2026 at 12:06:28PM +0100, Ulf Hansson wrote:

quoted

On Mon, 2 Feb 2026 at 08:46, Xu Yang [off-list ref] wrote:

quoted

+
+               list_for_each_entry(pdd, &domain->genpd.dev_list, list_node) {
+                       if (device_awake_path(pdd->dev)) {
+                               device_set_awake_path(domain->power_dev);
+                               break;
+                       }
+               }

This is really messy in my opinion. Ideally the above should not be
used by a genpd provider as it's internal data structures are managed
by genpd itself.

If I understand correctly, this problem boils down to the fact that we
should have tried harder to model child/parent domains, rather than
using runtime PM to manage the parent domains. I understand there are
problems with that, due to specific power on/off sequences we have for
imx power-domains, but I wonder if those could be managed better by
using genpd on/off notifiers?

Indeed. I have tried using subdomain will resolve the wakeup issue because
the parent domain will manage the child domain. But I shouldn't use
subdomain and runtime PM way together to avoid any unexpected behaviors
according to my understanding.

Well, there is nothing wrong with using child/parent domain in
combination with runtime PM.

Although in general using runtime PM to manage parents domains from
child domains, should be better managed by genpd itself.

quoted

Anyway, that said. Rather than walking through the list of devices as
above, I suggest that you use the ->power_off() callback for the
corresponding genpd(s) to dev in combination with a genpd power on/off
notifier for the corresponding genpd that the power_dev is attached
to.

More precisely, if the "child domain(s)" that corresponds to "dev" has
not been powered-off (because device_awake_path() is set for some
device) during system suspend, the power-off notifier should return
NOTIFY_BAD to prevent the "parent domain" that corresponds to
power_dev from being powered-off.

Would that work, you think?

Thank you for the suggestion. It works for me.

Great!

With this way the rejected count is increasing. Does this have any impact?
The count is just used for statistics, right?

Yes, it's used for statistics.

# cat /sys/kernel/debug/pm_genpd/usb-otg2/idle_states
State          Time Spent(ms) Usage      Rejected   Above      Below
S0             1203           0          1          0          0

Thanks,
Xu Yang

Kind regards
Uffe