linux-kernel - Re: [PATCH 4/5] power: supply: bq27xxx: Look for status change on external power change

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Date:   Fri, 5 May 2017 10:04:58 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Paul Kocialkowski <contact@...lk.fr>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Andrew F . Davis" <afd@...com>,
        Sebastian Reichel <sre@...nel.org>,
        Chris Lapa <chris@...a.com.au>,
        Matt Ranostay <mranostay@...il.com>
Subject: Re: [PATCH 4/5] power: supply: bq27xxx: Look for status change on
 external power change

On Sunday 30 April 2017 20:27:26 Paul Kocialkowski wrote:
> This introduces a dedicated status change work to look for power
> status change. It is triggered by external power change notifications
> and periodically retries detecting a power status change for 5 seconds.
> 
> This is largely inspired by a similar mechanism from the sbs-battery
> driver.

What is reason/motivation for such change? It should be written in
commit message (to help understand; not only for me), because really I
do not know why such patch is needed.

> Signed-off-by: Paul Kocialkowski <contact@...lk.fr>
> ---
>  drivers/power/supply/bq27xxx_battery.c | 38 ++++++++++++++++++++++++++++++++--
>  include/linux/power/bq27xxx_battery.h  |  3 +++
>  2 files changed, 39 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
> index 926bd58344d9..cade00df6162 100644
> --- a/drivers/power/supply/bq27xxx_battery.c
> +++ b/drivers/power/supply/bq27xxx_battery.c
> @@ -1190,6 +1190,11 @@ static int bq27xxx_battery_status(struct bq27xxx_device_info *di,
>  			status = POWER_SUPPLY_STATUS_CHARGING;
>  	}
>  
> +	if (di->status_retry == 0 && di->status_change_reference != status) {
> +		di->status_change_reference = status;
> +		power_supply_changed(di->bat);
> +	}
> +
>  	val->intval = status;
>  
>  	return 0;
> @@ -1340,12 +1345,38 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
>  	return ret;
>  }
>  
> +static void bq27xxx_status_change(struct work_struct *work)
> +{
> +	struct bq27xxx_device_info *di =
> +			container_of(work, struct bq27xxx_device_info,
> +				     status_work.work);
> +	union power_supply_propval val;
> +	int ret;
> +
> +	bq27xxx_battery_update(di);
> +
> +	ret = bq27xxx_battery_status(di, &val);
> +	if (ret < 0)
> +		return;
> +
> +	if (di->status_change_reference != val.intval) {
> +		di->status_change_reference = val.intval;
> +		power_supply_changed(di->bat);
> +	}
> +
> +	if (di->status_retry > 0) {
> +		di->status_retry--;
> +		schedule_delayed_work(&di->status_work, HZ);
> +	}
> +}
> +
>  static void bq27xxx_external_power_changed(struct power_supply *psy)
>  {
>  	struct bq27xxx_device_info *di = power_supply_get_drvdata(psy);
>  
> -	cancel_delayed_work_sync(&di->poll_work);
> -	schedule_delayed_work(&di->poll_work, 0);
> +	cancel_delayed_work_sync(&di->status_work);
> +	schedule_delayed_work(&di->status_work, HZ);
> +	di->status_retry = 5;
>  }
>  
>  int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
> @@ -1357,8 +1388,10 @@ int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
>  	psy_cfg.of_node = di->of_node;
>  
>  	INIT_DELAYED_WORK(&di->poll_work, bq27xxx_battery_poll);
> +	INIT_DELAYED_WORK(&di->status_work, bq27xxx_status_change);
>  	mutex_init(&di->lock);
>  	di->regs = bq27xxx_regs[di->chip];
> +	di->status_change_reference = POWER_SUPPLY_STATUS_UNKNOWN;
>  
>  	psy_desc = devm_kzalloc(di->dev, sizeof(*psy_desc), GFP_KERNEL);
>  	if (!psy_desc)
> @@ -1400,6 +1433,7 @@ void bq27xxx_battery_teardown(struct bq27xxx_device_info *di)
>  	poll_interval = 0;
>  
>  	cancel_delayed_work_sync(&di->poll_work);
> +	cancel_delayed_work_sync(&di->status_work);
>  
>  	power_supply_unregister(di->bat);
>  
> diff --git a/include/linux/power/bq27xxx_battery.h b/include/linux/power/bq27xxx_battery.h
> index 0a9af513165a..16d604681ace 100644
> --- a/include/linux/power/bq27xxx_battery.h
> +++ b/include/linux/power/bq27xxx_battery.h
> @@ -67,6 +67,9 @@ struct bq27xxx_device_info {
>  	int charge_design_full;
>  	unsigned long last_update;
>  	struct delayed_work poll_work;
> +	struct delayed_work status_work;
> +	int status_retry;
> +	int status_change_reference;
>  	struct power_supply *bat;
>  	struct list_head list;
>  	struct mutex lock;

-- 
Pali Rohár
pali.rohar@...il.com