linux-kernel - Re: [PATCH v2] charger_manager: update charge profile upon temperature zone change

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Date:	Tue, 08 May 2012 00:01:12 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	Ramakrishna Pallala <ramakrishna.pallala@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	Anton Vorontsov <cbouatmailru@...il.com>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	최찬우 <cw00.choi@...sung.com>
Subject: Re: [PATCH v2] charger_manager: update charge profile upon temperature
 zone change

> Battery vendors like UER suggest to program Low Charge Voltage in case
> of high or low temperatures. So a battery can have different charge profile
> with in the battery operating temperature limits.
> 
> Next, there could be events like drop or rise in VBUS voltage in that case
> we might have to adjust the charge current to stabilize VBUS voltage.
> 
> This patch allows the Charger-Manager to adjust the charging parameters
> upon events like VBUS rise or drop and allows batteries to have multiple
> charge profiles for different temperature zones.
> 
> Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@...el.com>

I don't see how the parameters are changed when update_charger is true.

Are you intending to do it at userspace after getting uevent_notify()? (I don't think it's good)

If the intension is to update some of the charger-manager internal parameters (struct charger_manager's struct charger_desc) according to the temperature, we'd need a more general method that can also update values in the charger-manager context.

For example, instead of simply putting a callback to determine whether an update is required or not, a table of (including hysterisis) temperatures and values to be updated (or callbacks to update charger_desc based on the temperature) might be a starting point. You may also need to consider using notifier chain w/ temperatures.

Cheers!
MyungJoo.

> ---
>  Documentation/power/charger-manager.txt |   10 ++++++++++
>  drivers/power/charger-manager.c         |    6 +++++-
>  include/linux/power/charger-manager.h   |    5 +++++
>  3 files changed, 20 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/power/charger-manager.txt b/Documentation/power/charger-manager.txt
> index b4f7f4b..6fa2a10 100644
> --- a/Documentation/power/charger-manager.txt
> +++ b/Documentation/power/charger-manager.txt
> @@ -50,6 +50,15 @@ Charger Manager supports the following:
>  	restarts charging. This check is also performed while suspended by
>  	setting wakeup time accordingly and using suspend_again.
>  
> +* Support for adjusting charging parameters
> +	Batteries can have different charge profiles with in the battery
> +	operating temperature limits. And events like drop or rise in VBUS
> +	voltage require adjustment of charge current to stabilize VBUS voltage.
> +
> +	Charger Manager provides a function pointer "charging_zone_changed" which
> +	can be implemented by platform/core drivers and Charger Manager checks
> +	this function to update the charger.
> +
>  * Support for uevent-notify
>  	With the charger-related events, the device sends
>  	notification to users with UEVENT.
> @@ -169,6 +178,7 @@ char *psy_fuel_gauge;
>  	: Power-supply-class name of the fuel gauge.
>  
>  int (*temperature_out_of_range)(int *mC);
> +bool (*charging_zone_changed)(int mC);
>  bool measure_battery_temp;
>  	: This callback returns 0 if the temperature is safe for charging,
>  	a positive number if it is too hot to charge, and a negative number
> diff --git a/drivers/power/charger-manager.c b/drivers/power/charger-manager.c
> index 86935ec..9f46353 100644
> --- a/drivers/power/charger-manager.c
> +++ b/drivers/power/charger-manager.c
> @@ -424,13 +424,17 @@ static void fullbatt_vchk(struct work_struct *work)
>  static bool _cm_monitor(struct charger_manager *cm)
>  {
>  	struct charger_desc *desc = cm->desc;
> +	bool update_charger = false;
>  	int temp = desc->temperature_out_of_range(&cm->last_temp_mC);
>  
>  	dev_dbg(cm->dev, "monitoring (%2.2d.%3.3dC)\n",
>  		cm->last_temp_mC / 1000, cm->last_temp_mC % 1000);
>  
> +	if (desc->charging_zone_changed)
> +		update_charger = desc->charging_zone_changed(cm->last_temp_mC);
> +
>  	/* It has been stopped or charging already */
> -	if (!!temp == !!cm->emergency_stop)
> +	if ((!!temp == !!cm->emergency_stop) && !update_charger)
>  		return false;
>  
>  	if (temp) {
> diff --git a/include/linux/power/charger-manager.h b/include/linux/power/charger-manager.h
> index 241065c..302107d 100644
> --- a/include/linux/power/charger-manager.h
> +++ b/include/linux/power/charger-manager.h
> @@ -90,6 +90,10 @@ struct charger_global_desc {
>   *	return_value > 0: overheat
>   *	return_value == 0: normal
>   *	return_value < 0: cold
> + * @charging_zone_changed:
> + *	Determine whether charge profile need an update
> + *	return_value true if charge profile update required
> + *	return_value false if charge profile update is not required
>   * @measure_battery_temp:
>   *	true: measure battery temperature
>   *	false: measure ambient temperature
> @@ -114,6 +118,7 @@ struct charger_desc {
>  	char *psy_fuel_gauge;
>  
>  	int (*temperature_out_of_range)(int *mC);
> +	bool (*charging_zone_changed)(int mC);
>  	bool measure_battery_temp;
>  };
>  
> -- 
> 1.7.0.4
> 
>