PM: domains: Detach on device_unbind_cleanup()

The dev_pm_domain_attach() function is typically used in bus code
alongside dev_pm_domain_detach(), often following patterns like:

static int bus_probe(struct device *_dev)
{
    struct bus_driver *drv = to_bus_driver(dev->driver);
    struct bus_device *dev = to_bus_device(_dev);
    int ret;

    // ...

    ret = dev_pm_domain_attach(_dev, true);
    if (ret)
        return ret;

    if (drv->probe)
        ret = drv->probe(dev);

    // ...
}

static void bus_remove(struct device *_dev)
{
    struct bus_driver *drv = to_bus_driver(dev->driver);
    struct bus_device *dev = to_bus_device(_dev);

    if (drv->remove)
        drv->remove(dev);
    dev_pm_domain_detach(_dev);
}

When the driver's probe function uses devres-managed resources that
depend on the power domain state, those resources are released later
during device_unbind_cleanup().

Releasing devres-managed resources that depend on the power domain state
after detaching the device from its PM domain can cause failures.

For example, if the driver uses devm_pm_runtime_enable() in its probe
function, and the device's clocks are managed by the PM domain, then
during removal the runtime PM is disabled in device_unbind_cleanup()
after the clocks have been removed from the PM domain. It may happen
that the devm_pm_runtime_enable() action causes the device to be runtime-
resumed. If the driver specific runtime PM APIs access registers directly,
this will lead to accessing device registers without clocks being enabled.
Similar issues may occur with other devres actions that access device
registers.

Add detach_power_off member to struct dev_pm_info, to be used
later in device_unbind_cleanup() as the power_off argument for
dev_pm_domain_detach(). This is a preparatory step toward removing
dev_pm_domain_detach() calls from bus remove functions. Since the current
PM domain detach functions (genpd_dev_pm_detach() and acpi_dev_pm_detach())
already set dev->pm_domain = NULL, there should be no issues with bus
drivers that still call dev_pm_domain_detach() in their remove functions.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/20250703112708.1621607-3-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: claudiubeznea

drivers/base/dd.c

@@ -25,6 +25,7 @@
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/async.h>
+#include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 #include <linux/pinctrl/devinfo.h>
 #include <linux/slab.h>
@@ -552,6 +553,7 @@ static void device_unbind_cleanup(struct device *dev)
 	dev->dma_range_map = NULL;
 	device_set_driver(dev, NULL);
 	dev_set_drvdata(dev, NULL);
+	dev_pm_domain_detach(dev, dev->power.detach_power_off);
 	if (dev->pm_domain && dev->pm_domain->dismiss)
 		dev->pm_domain->dismiss(dev);
 	pm_runtime_reinit(dev);

drivers/base/power/common.c

@@ -111,6 +111,9 @@ int dev_pm_domain_attach(struct device *dev, u32 flags)
 	if (!ret)
 		ret = genpd_dev_pm_attach(dev);
 
+	if (dev->pm_domain)
+		dev->power.detach_power_off = !!(flags & PD_FLAG_DETACH_POWER_OFF);
+
 	return ret < 0 ? ret : 0;
 }
 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);

include/linux/pm.h

@@ -721,6 +721,7 @@ struct dev_pm_info {
 	struct pm_subsys_data	*subsys_data;  /* Owned by the subsystem. */
 	void (*set_latency_tolerance)(struct device *, s32);
 	struct dev_pm_qos	*qos;
+	bool			detach_power_off:1;	/* Owned by the driver core */
 };
 
 extern int dev_pm_get_subsys_data(struct device *dev);