Commit 965a9904 authored by Linus Walleij's avatar Linus Walleij Committed by Sebastian Reichel
Browse files

power: supply: ab8500_fg: Safeguard compensated voltage 



In some cases when the platform is dissapating more than
500mA the voltage measurements and compensation will become
instable. Add a parameter to bail out of the voltage
measurement if this happens.

This code was found in a Samsung vendor tree.

Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarSebastian Reichel <sebastian.reichel@collabora.com>
parent 673b5032

drivers/power/supply/ab8500_fg.c

+13 −2
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ 


#define NBR_AVG_SAMPLES			20

#define WAIT_FOR_INST_CURRENT_MAX	70

/* Currents higher than -500mA (dissipating) will make compensation unstable */

#define IGNORE_VBAT_HIGHCUR		-500000



#define LOW_BAT_CHECK_INTERVAL		(HZ / 16) /* 62.5 ms */
@@ -911,12 +913,13 @@ static int ab8500_fg_battery_resistance(struct ab8500_fg *di) 
/**

 * ab8500_load_comp_fg_bat_voltage() - get load compensated battery voltage

 * @di:		pointer to the ab8500_fg structure

 * @always:	always return a voltage, also uncompensated

 *

 * Returns compensated battery voltage (on success) else error code.

 * If always is specified, we always return a voltage but it may be

 * uncompensated.

 */

static int ab8500_load_comp_fg_bat_voltage(struct ab8500_fg *di)

static int ab8500_load_comp_fg_bat_voltage(struct ab8500_fg *di, bool always)

{

	int i = 0;

	int vbat_uv = 0;
@@ -941,6 +944,14 @@ static int ab8500_load_comp_fg_bat_voltage(struct ab8500_fg *di) 


	ab8500_fg_inst_curr_finalize(di, &di->inst_curr_ua);



	/*

	 * If there is too high current dissipation, the compensation cannot be

	 * trusted so return an error unless we must return something here, as

	 * enforced by the "always" parameter.

	 */

	if (!always && di->inst_curr_ua < IGNORE_VBAT_HIGHCUR)

		return -EINVAL;



	vbat_uv = vbat_uv / i;



	/* Next we apply voltage compensation from internal resistance */
@@ -964,7 +975,7 @@ static int ab8500_fg_load_comp_volt_to_capacity(struct ab8500_fg *di) 
{

	int vbat_comp_uv;



	vbat_comp_uv = ab8500_load_comp_fg_bat_voltage(di);

	vbat_comp_uv = ab8500_load_comp_fg_bat_voltage(di, true);



	return ab8500_fg_volt_to_capacity(di, vbat_comp_uv);

}