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power: pm8921-bms: increase accuracy of voltage during charging adjusting

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During charging adjustment, the measurement of voltage is not accurate.
Since the measured voltage during charging adjustment is not OCV
(open circuit voltage), it cannot show real battery voltage at CC to CV
point. But current implementation use inaccurate voltage as a voltage of
CC to CV point. This inaccurate voltage of CC to CV point can cause
wrong SoC adjusting. For instance, the SoC could stick at fixed value
until end of charging.
This patch increase accuracy of voltage measurement by using battery
current and battery resister.

Change-Id: I3a4cc4e58e409be5422ec6bf64678a9a92b9fe25
This commit is contained in:
choongryeol.lee 2013-01-25 17:49:30 -08:00 committed by Iliyan Malchev
parent 1819bd4e44
commit 37c59c5e44
1 changed files with 10 additions and 8 deletions
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18
drivers/power/pm8921-bms.c
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@ -130,7 +130,7 @@ struct pm8921_bms_chip {
int default_rbatt_mohm;
int amux_2_trim_delta;
uint16_t prev_last_good_ocv_raw;
unsigned int rconn_mohm;
int rconn_mohm;
struct mutex last_ocv_uv_mutex;
int last_ocv_uv;
int pon_ocv_uv;
@ -1652,6 +1652,8 @@ static int charging_adjustments(struct pm8921_bms_chip *chip,
int chg_soc;
int max_vol;
int eoc_current;
int vbat_batt_terminal_uv = vbat_uv
+ (ibat_ua * chip->rconn_mohm) / 1000;
max_vol = chip->max_voltage_uv;
eoc_current = -chip->chg_term_ua;
@ -1663,15 +1665,15 @@ static int charging_adjustments(struct pm8921_bms_chip *chip,
if (chip->soc_at_cv == -EINVAL) {
/* In constant current charging return the calc soc */
if (vbat_uv <= max_vol)
if (vbat_batt_terminal_uv <= max_vol)
pr_debug("CC CHG SOC %d\n", soc);
/* Note the CC to CV point */
if (vbat_uv >= max_vol) {
if (vbat_batt_terminal_uv >= max_vol) {
chip->soc_at_cv = soc;
chip->prev_chg_soc = soc;
chip->ibat_at_cv_ua = ibat_ua;
chip->vbat_at_cv = vbat_uv;
chip->vbat_at_cv = max_vol;
pr_debug("CC_TO_CV ibat_ua = %d CHG SOC %d\n",
ibat_ua, soc);
}
@ -1680,7 +1682,7 @@ static int charging_adjustments(struct pm8921_bms_chip *chip,
chip->soc_at_cv = soc;
chip->prev_chg_soc = soc;
chip->ibat_at_cv_ua = ibat_ua;
chip->vbat_at_cv = vbat_uv;
chip->vbat_at_cv = vbat_batt_terminal_uv;
pr_debug("Force CC_TO_CV ibat_ua = %d CHG SOC %d\n",
ibat_ua, soc);
}
@ -1696,9 +1698,9 @@ static int charging_adjustments(struct pm8921_bms_chip *chip,
* if voltage lessened (possibly because of a system load)
* keep reporting the prev chg soc
*/
if (vbat_uv <= chip->vbat_at_cv) {
if (vbat_batt_terminal_uv <= chip->vbat_at_cv) {
pr_debug("vbat %d < max = %d CC CHG SOC %d\n",
vbat_uv, chip->vbat_at_cv, chip->prev_chg_soc);
vbat_batt_terminal_uv, chip->vbat_at_cv, chip->prev_chg_soc);
return chip->prev_chg_soc;
}
@ -1706,7 +1708,7 @@ static int charging_adjustments(struct pm8921_bms_chip *chip,
&& chip->wlc_is_plugged()
&& chip->prev_chg_soc < 99
&& ibat_ua > eoc_current) {
pr_info("ibat < eco_current ! soc = %d \n", chip->prev_chg_soc);
pr_info("ibat < eoc_current ! soc = %d \n", chip->prev_chg_soc);
return chip->prev_chg_soc;
}