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Commit 908fe8d6 authored by Hakan Berg's avatar Hakan Berg Committed by Lee Jones
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ab8500-btemp: Filter btemp readings 



Battery tempreature readings sometimes fail and results in
a value far from recent values. This patch adds a software
filter that disposes such readings, by allowing direct
updates on temperature only if two samples result in the
same temperature. Else only allow 1 degree change from previous
reported value in the direction of the new measurement.

Signed-off-by: default avatarHakan Berg <hakan.berg@stericsson.com>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
Reviewed-by: default avatarMarcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: default avatarMartin SJOBLOM <martin.w.sjoblom@stericsson.com>
Reviewed-by: default avatarRabin VINCENT <rabin.vincent@stericsson.com>
parent d4f510f6

drivers/power/ab8500_btemp.c

+21 −6
Original line number Diff line number Diff line
@@ -76,8 +76,8 @@ struct ab8500_btemp_ranges { 
 * @dev:		Pointer to the structure device

 * @node:		List of AB8500 BTEMPs, hence prepared for reentrance

 * @curr_source:	What current source we use, in uA

 * @bat_temp:		Battery temperature in degree Celcius

 * @prev_bat_temp	Last dispatched battery temperature

 * @bat_temp:		Dispatched battery temperature in degree Celcius

 * @prev_bat_temp	Last measured battery temperature in degree Celcius

 * @parent:		Pointer to the struct ab8500

 * @gpadc:		Pointer to the struct gpadc

 * @fg:			Pointer to the struct fg
@@ -604,6 +604,7 @@ static int ab8500_btemp_id(struct ab8500_btemp *di) 
static void ab8500_btemp_periodic_work(struct work_struct *work)

{

	int interval;

	int bat_temp;

	struct ab8500_btemp *di = container_of(work,

		struct ab8500_btemp, btemp_periodic_work.work);
@@ -614,12 +615,26 @@ static void ab8500_btemp_periodic_work(struct work_struct *work) 
			dev_warn(di->dev, "failed to identify the battery\n");

	}



	di->bat_temp = ab8500_btemp_measure_temp(di);



	if (di->bat_temp != di->prev_bat_temp) {

		di->prev_bat_temp = di->bat_temp;

	bat_temp = ab8500_btemp_measure_temp(di);

	/*

	 * Filter battery temperature.

	 * Allow direct updates on temperature only if two samples result in

	 * same temperature. Else only allow 1 degree change from previous

	 * reported value in the direction of the new measurement.

	 */

	if (bat_temp == di->prev_bat_temp || !di->initialized) {

		if (di->bat_temp != di->prev_bat_temp || !di->initialized) {

			di->bat_temp = bat_temp;

			power_supply_changed(&di->btemp_psy);

		}

	} else if (bat_temp < di->prev_bat_temp) {

		di->bat_temp--;

		power_supply_changed(&di->btemp_psy);

	} else if (bat_temp > di->prev_bat_temp) {

		di->bat_temp++;

		power_supply_changed(&di->btemp_psy);

	}

	di->prev_bat_temp = bat_temp;



	if (di->events.ac_conn || di->events.usb_conn)

		interval = di->bm->temp_interval_chg;