Re: [PATCH] arm64: defconfig: Enable cros-ec and battery driver

[Thierry Reding <treding@nvidia.com>]

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On Wed, May 25, 2016 at 12:03:47PM +0100, Jon Hunter wrote:
> 
> On 25/05/16 11:58, Jon Hunter wrote:
> 
> ...
> 
> > Looking at this a bit more I am wondering if we should prevent the
> > battery for being polled before the registration has completed ...
> > 
> > diff --git a/drivers/power/bq27xxx_battery.c
> > b/drivers/power/bq27xxx_battery.c
> > index 45f6ebf88df6..32649183ecd9 100644
> > --- a/drivers/power/bq27xxx_battery.c
> > +++ b/drivers/power/bq27xxx_battery.c
> > @@ -871,12 +871,14 @@ static int bq27xxx_battery_get_property(struct
> > power_supply *psy,
> >         int ret = 0;
> >         struct bq27xxx_device_info *di = power_supply_get_drvdata(psy);
> > 
> > -       mutex_lock(&di->lock);
> > -       if (time_is_before_jiffies(di->last_update + 5 * HZ)) {
> > -               cancel_delayed_work_sync(&di->work);
> > -               bq27xxx_battery_poll(&di->work.work);
> > +       if (di->bat) {
> > +               mutex_lock(&di->lock);
> > +               if (time_is_before_jiffies(di->last_update + 5 * HZ)) {
> > +                       cancel_delayed_work_sync(&di->work);
> > +                       bq27xxx_battery_poll(&di->work.work);
> > +               }
> > +               mutex_unlock(&di->lock);
> >         }
> > -       mutex_unlock(&di->lock);
> 
> Alternatively, maybe the following is simpler ...
> 
> diff --git a/drivers/power/bq27xxx_battery.c
> b/drivers/power/bq27xxx_battery.c
> index 45f6ebf88df6..8a713b52e9f6 100644
> --- a/drivers/power/bq27xxx_battery.c
> +++ b/drivers/power/bq27xxx_battery.c
> @@ -733,7 +733,8 @@ static void bq27xxx_battery_poll(struct work_struct
> *work)
>                         container_of(work, struct bq27xxx_device_info,
>                                      work.work);
> 
> -       bq27xxx_battery_update(di);
> +       if (di->bat)
> +               bq27xxx_battery_update(di);

How about this, which should be the most minimal to fix it (though it's
completely untested) and still update the internal cache (it just won't
signal an supply change, which wouldn't work at this point anyway). The
patch makes up for the supply change notification by doing that instead
of a full bq27xxx_battery_update() at the end of ->probe(). This should
take care of always sending out a uevent on successful probe, whereas a
bq27xxx_battery_update() at the end of ->probe() may not send one if it
is presented with the same data.

Thierry
--- >8 ---
diff --git a/drivers/power/bq27xxx_battery.c b/drivers/power/bq27xxx_battery.c
index 45f6ebf88df6..df1b4cb2bbc2 100644
--- a/drivers/power/bq27xxx_battery.c
+++ b/drivers/power/bq27xxx_battery.c
@@ -717,7 +717,13 @@ void bq27xxx_battery_update(struct bq27xxx_device_info *di)
 			di->charge_design_full = bq27xxx_battery_read_dcap(di);
 	}
 
-	if (di->cache.capacity != cache.capacity)
+	/*
+	 * This function ends up being called while the power supply is being
+	 * registered, hence di->bat will be NULL on the first call, causing
+	 * power_supply_changed() to oops. Avoid that by checking if we have
+	 * been registered already or not.
+	 */
+	if (di->bat && di->cache.capacity != cache.capacity)
 		power_supply_changed(di->bat);
 
 	if (memcmp(&di->cache, &cache, sizeof(cache)) != 0)
@@ -984,7 +990,7 @@ int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
 
 	dev_info(di->dev, "support ver. %s enabled\n", DRIVER_VERSION);
 
-	bq27xxx_battery_update(di);
+	power_supply_changed(di->bat);
 
 	return 0;
 }

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