linux-kernel - Re: [PATCH 2/2] power: bq27xxx_battery: allow kernel poll

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Date:   Mon, 19 Sep 2016 21:49:31 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Matt Ranostay <mranostay@...il.com>
Cc:     "Andrew F . Davis" <afd@...com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Matt Ranostay <matt@...ostay.consulting>
Subject: Re: [PATCH 2/2] power: bq27xxx_battery: allow kernel poll_interval
 parameter runtime update

Hi,

On Fri, Sep 16, 2016 at 08:42:55PM -0700, Matt Ranostay wrote:
> Fix issue with poll_interval being not updated till the previous
> interval expired.
> 
> Signed-off-by: Matt Ranostay <matt@...ostay.consulting>
> ---
>  drivers/power/supply/bq27xxx_battery.c | 38 +++++++++++++++++++++++++++++++++-
>  include/linux/power/bq27xxx_battery.h  |  1 +
>  2 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
> index 955424e10ae2..96fd3eec98da 100644
> --- a/drivers/power/supply/bq27xxx_battery.c
> +++ b/drivers/power/supply/bq27xxx_battery.c
> @@ -39,6 +39,7 @@
>  
>  #include <linux/device.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/param.h>
>  #include <linux/jiffies.h>
>  #include <linux/workqueue.h>
> @@ -390,8 +391,35 @@ static struct {
>  	BQ27XXX_PROP(BQ27421, bq27421_battery_props),
>  };
>  
> +static DEFINE_MUTEX(param_lock);
> +static LIST_HEAD(bq27xxx_battery_devices);
> +
> +static int poll_interval_param_set(const char *val, const struct kernel_param *kp)
> +{
> +	struct bq27xxx_device_info *di;
> +	int ret;
> +
> +	ret = param_set_uint(val, kp);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_lock(&param_lock);
> +	list_for_each_entry(di, &bq27xxx_battery_devices, list) {
> +		cancel_delayed_work_sync(&di->work);
> +		schedule_delayed_work(&di->work, 0);
> +	}
> +	mutex_unlock(&param_lock);
> +
> +	return ret;
> +}
> +
> +static const struct kernel_param_ops param_ops_poll_interval = {
> +	.get = param_get_ushort,

param_get_uint?

> +	.set = poll_interval_param_set,
> +};
> +
>  static unsigned int poll_interval = 360;
> -module_param(poll_interval, uint, 0644);
> +module_param_cb(poll_interval, &param_ops_poll_interval, &poll_interval, 0644);
>  MODULE_PARM_DESC(poll_interval,
>  		 "battery poll interval in seconds - 0 disables polling");
>  
> @@ -1011,6 +1039,10 @@ int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
>  
>  	bq27xxx_battery_update(di);
>  
> +	mutex_lock(&param_lock);
> +	list_add(&di->list, &bq27xxx_battery_devices);
> +	mutex_unlock(&param_lock);
> +
>  	return 0;
>  
>  err_out:
> @@ -1036,6 +1068,10 @@ void bq27xxx_battery_teardown(struct bq27xxx_device_info *di)
>  
>  	power_supply_unregister(di->bat);
>  
> +	mutex_lock(&param_lock);
> +	list_del(&di->list);
> +	mutex_unlock(&param_lock);
> +
>  	mutex_destroy(&di->lock);
>  }
>  EXPORT_SYMBOL_GPL(bq27xxx_battery_teardown);
> diff --git a/include/linux/power/bq27xxx_battery.h b/include/linux/power/bq27xxx_battery.h
> index b50c0492629d..e30deb046156 100644
> --- a/include/linux/power/bq27xxx_battery.h
> +++ b/include/linux/power/bq27xxx_battery.h
> @@ -58,6 +58,7 @@ struct bq27xxx_device_info {
>  	unsigned long last_update;
>  	struct delayed_work work;
>  	struct power_supply *bat;
> +	struct list_head list;
>  	struct mutex lock;
>  	u8 *regs;
>  };

Looks fine otherwise. When you redo the patch it would be nice to
rename param_lock into something like bq27xxx_list_lock instead,
though.

-- Sebastian

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