[PATCH v2] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

[Sudeep Holla <sudeep.holla@arm.com>]

If the genpd->attach_dev or genpd->power_on fails, genpd_dev_pm_attach
may return -EPROBE_DEFER initially. However genpd_alloc_dev_data sets
the PM domain for the device unconditionally.

When subsequent attempts are made to call genpd_dev_pm_attach, it may
return -EEXISTS checking dev->pm_domain without re-attempting to call
attach_dev or power_on.

platform_drv_probe then attempts to call drv->probe as the return value
-EEXIST != -EPROBE_DEFER, which may end up in a situation where the
device is accessed without it's power domain switched on.

Fixes: f104e1e5ef57 ("PM / Domains: Re-order initialization of generic_pm_domain_data")
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: <stable@vger.kernel.org> # v4.0+
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/base/power/domain.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Hi,

I have added Cc/Fixes tags based on the original commit that caused the issue.
I need to workout a patch that can cleanly apply before commit 989561de9b51
("PM / Domains: add setter for dev.pm_domain"), i.e. for v4.0.x to v4.4.x
This patch should apply from v4.5.x onwards.

Let me know if I got anything wrong.

v1->v2: Moved dev_pm_domain_set(dev, NULL) from genpd_free_dev_data

Regards,
Sudeep

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index da49a8383dc3..2d9178660061 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1168,8 +1168,6 @@ static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
 
 	spin_unlock_irq(&dev->power.lock);
 
-	dev_pm_domain_set(dev, &genpd->domain);
-
 	return gpd_data;
 
  err_free:
@@ -1183,8 +1181,6 @@ static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
 static void genpd_free_dev_data(struct device *dev,
 				struct generic_pm_domain_data *gpd_data)
 {
-	dev_pm_domain_set(dev, NULL);
-
 	spin_lock_irq(&dev->power.lock);
 
 	dev->power.subsys_data->domain_data = NULL;
@@ -1221,6 +1217,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (ret)
 		goto out;
 
+	dev_pm_domain_set(dev, &genpd->domain);
+
 	genpd->device_count++;
 	genpd->max_off_time_changed = true;
 
@@ -1282,6 +1280,8 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
 	if (genpd->detach_dev)
 		genpd->detach_dev(genpd, dev);
 
+	dev_pm_domain_set(dev, NULL);
+
 	list_del_init(&pdd->list_node);
 
 	genpd_unlock(genpd);
-- 
2.7.4