PM: domains: Add flags to specify power on attach/detach

Calling dev_pm_domain_attach()/dev_pm_domain_detach() in bus driver
probe/remove functions can affect system behavior when the drivers
attached to the bus use devres-managed resources. Since devres actions
may need to access device registers, calling dev_pm_domain_detach() too
early, i.e., before these actions complete, can cause failures on some
systems. One such example is Renesas RZ/G3S SoC-based platforms.

If the device clocks are managed via PM domains, invoking
dev_pm_domain_detach() in the bus driver's remove function removes the
device's clocks from the PM domain, preventing any subsequent
pm_runtime_resume*() calls from enabling those clocks.

The second argument of dev_pm_domain_attach() specifies whether the PM
domain should be powered on during attachment. Likewise, the second
argument of dev_pm_domain_detach() indicates whether the domain should be
powered off during detachment.

Upcoming changes address the issue described above (initially for the
platform bus only) by deferring the call to dev_pm_domain_detach() until
after devres_release_all() in device_unbind_cleanup(). The detach_power_off
field in struct dev_pm_info stores the detach power off info from the
second argument of dev_pm_domain_attach().

Because there are cases where the device's PM domain power-on/off behavior
must be conditional (e.g., in i2c_device_probe()), the patch introduces
PD_FLAG_ATTACH_POWER_ON and PD_FLAG_DETACH_POWER_OFF flags to be passed
to dev_pm_domain_attach().

Finally, dev_pm_domain_attach() and its users are updated to use the newly
introduced PD_FLAG_ATTACH_POWER_ON and PD_FLAG_DETACH_POWER_OFF macros.

This change is preparatory.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com> # I2C
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/20250703112708.1621607-2-claudiu.beznea.uj@bp.renesas.com
[ rjw: Changelog adjustments ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 0b18160901a2..62a35a78ce9b 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -36,10 +36,16 @@
  *				isn't specified, the index just follows the
  *				index for the attached PM domain.
  *
+ * PD_FLAG_ATTACH_POWER_ON:	Power on the domain during attach.
+ *
+ * PD_FLAG_DETACH_POWER_OFF:	Power off the domain during detach.
+ *
  */
 #define PD_FLAG_NO_DEV_LINK		BIT(0)
 #define PD_FLAG_DEV_LINK_ON		BIT(1)
 #define PD_FLAG_REQUIRED_OPP		BIT(2)
+#define PD_FLAG_ATTACH_POWER_ON		BIT(3)
+#define PD_FLAG_DETACH_POWER_OFF	BIT(4)
 
 struct dev_pm_domain_attach_data {
 	const char * const *pd_names;
@@ -501,7 +507,7 @@ struct generic_pm_domain *of_genpd_remove_last(struct device_node *np)
 #endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
 
 #ifdef CONFIG_PM
-int dev_pm_domain_attach(struct device *dev, bool power_on);
+int dev_pm_domain_attach(struct device *dev, u32 flags);
 struct device *dev_pm_domain_attach_by_id(struct device *dev,
 					  unsigned int index);
 struct device *dev_pm_domain_attach_by_name(struct device *dev,
@@ -518,7 +524,7 @@ int dev_pm_domain_start(struct device *dev);
 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd);
 int dev_pm_domain_set_performance_state(struct device *dev, unsigned int state);
 #else
-static inline int dev_pm_domain_attach(struct device *dev, bool power_on)
+static inline int dev_pm_domain_attach(struct device *dev, u32 flags)
 {
 	return 0;
 }