power_supply: fix return value of get_property

power_supply_get_property() should ideally return -EAGAIN if it is
called while the power_supply is being registered. There was no way
previously to determine if use_cnt == 0 meant that the power_supply
wasn't fully registered yet, or if it had already been unregistered.

Add a new boolean to the power_supply struct to simply show if
registration is completed. Lastly, modify the check in
power_supply_show_property() to also ignore -EAGAIN when so it
doesn't complain about not returning the property.

Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

3 files changed, 7 insertions, 2 deletions

diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 456987c88baa..c2ef0c0dfa9d 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -491,8 +491,11 @@ int power_supply_get_property(struct power_supply *psy,
                             enum power_supply_property psp,
                             union power_supply_propval *val)
 {
-        if (atomic_read(&psy->use_cnt) <= 0)
+        if (atomic_read(&psy->use_cnt) <= 0) {
+                if (!psy->initialized)
+                        return -EAGAIN;
                 return -ENODEV;
+        }
 
         return psy->desc->get_property(psy, psp, val);
 }
@@ -780,6 +783,7 @@ __power_supply_register(struct device *parent,
          *    after calling power_supply_register()).
          */
         atomic_inc(&psy->use_cnt);
+        psy->initialized = true;
 
         queue_delayed_work(system_power_efficient_wq,
                            &psy->deferred_register_work,
diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c
index 80fed98832f9..bcde8d13476a 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -83,7 +83,7 @@ static ssize_t power_supply_show_property(struct device *dev,
                         if (ret == -ENODATA)
                                 dev_dbg(dev, "driver has no data for `%s' property\n",
                                         attr->attr.name);
-                        else if (ret != -ENODEV)
+                        else if (ret != -ENODEV && ret != -EAGAIN)
                                 dev_err(dev, "driver failed to report `%s' property: %zd\n",
                                         attr->attr.name, ret);
                         return ret;
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 751061790626..3965503315ef 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -248,6 +248,7 @@ struct power_supply {
         struct delayed_work deferred_register_work;
         spinlock_t changed_lock;
         bool changed;
+        bool initialized;
         atomic_t use_cnt;
 #ifdef CONFIG_THERMAL
         struct thermal_zone_device *tzd;