power: pm8921-bms: remove Dynamic Unusable Charge algorithm
The dynamic UUC algorithm changes the UUC as load, state of charge and
temperature changes. This uncontrolled behaviour causes unacceptable
jumps in state of charge numbers.
Replace the dynamic UUC algorithm with a simple average current based
UUC. The average current is calculated by remembering the load for last
few (16) samples. Also to maintain a reasonable UUC while charging, a
load of 300mA is assumed.
Note that the first time UUC is calculated we don't have load samples
and in that case the instantaneous current is used.
Since we now don't change the UUC with respect to max possible load
(itest), the usage of this value is removed. Also instead of failure
voltage we introduce cutoff voltage which represents the loaded voltage
by which the battery should be reported 0%.
Change-Id: Ia640164ee2c9690537308d4e840953824ba15b58
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
diff --git a/drivers/power/pm8921-bms.c b/drivers/power/pm8921-bms.c
index 2612760..4b177c4 100644
--- a/drivers/power/pm8921-bms.c
+++ b/drivers/power/pm8921-bms.c
@@ -83,8 +83,7 @@
struct device *dev;
struct dentry *dent;
unsigned int r_sense;
- unsigned int i_test;
- unsigned int v_failure;
+ unsigned int v_cutoff;
unsigned int fcc;
struct single_row_lut *fcc_temp_lut;
struct single_row_lut *fcc_sf_lut;
@@ -126,15 +125,10 @@
int pon_ocv_uv;
int last_cc_uah;
struct timeval t;
- int last_uuc_uah;
int enable_fcc_learning;
int shutdown_soc;
- int allow_soc_increase_without_chg;
int shutdown_soc_timer_expired;
struct delayed_work shutdown_soc_work;
- int timer_uuc_expired;
- struct delayed_work uuc_timer_work;
- int uuc_uah_iavg_prev;
};
/*
@@ -1155,7 +1149,7 @@
int unusable_uv, pc_unusable, uuc;
/* calculate unusable charge with itest */
- unusable_uv = (rbatt * i_ma) + (chip->v_failure * 1000);
+ unusable_uv = (rbatt * i_ma) + (chip->v_cutoff * 1000);
pc_unusable = calculate_pc(chip, unusable_uv, batt_temp, chargecycles);
uuc = (fcc_uah * pc_unusable) / 100;
pr_debug("For i_ma = %d, unusable_uv = %d unusable_pc = %d uuc = %d\n",
@@ -1163,30 +1157,6 @@
return uuc;
}
-#define SOC_RBATT_CHG 70
-#define SOC_RBATT_DISCHG 20
-
-static int uuc_iavg_div = 150;
-module_param(uuc_iavg_div, int, 0644);
-
-static int uuc_min_step_size = 120;
-module_param(uuc_min_step_size, int, 0644);
-
-static int uuc_multiplier = 1000;
-module_param(uuc_multiplier, int, 0644);
-
-#define UUC_TIMER_MS 120000
-
-static void uuc_timer_work(struct work_struct *work)
-{
- struct pm8921_bms_chip *chip = container_of(work,
- struct pm8921_bms_chip, uuc_timer_work.work);
-
- pr_debug("UUC Timer expired\n");
- /* indicates the system is done with the high load during bootup */
- chip->timer_uuc_expired = 1;
-}
-
static void calculate_iavg_ua(struct pm8921_bms_chip *chip, int cc_uah,
int *iavg_ua, int *delta_time_us)
{
@@ -1219,114 +1189,63 @@
chip->t = now;
}
-#define UUC_IAVG_THRESHOLD_UAH 50000
-static int scale_unusable_charge_uah(struct pm8921_bms_chip *chip,
- bool charging, int uuc_uah_iavg, int uuc_uah_itest,
- int uuc_uah_iavg_prev)
-{
- int stepsize = 0;
- int delta_uuc = 0;
- int uuc_reported = 0;
-
- if (charging) {
- stepsize = max(uuc_min_step_size,
- uuc_multiplier * (SOC_RBATT_CHG - last_soc));
- /*
- * set the delta only if uuc is decreasing. If it has increased
- * simply report the last uuc since we don't want to report a
- * higher uuc as charging progresses
- */
- if (chip->last_uuc_uah > uuc_uah_iavg)
- delta_uuc = (chip->last_uuc_uah - uuc_uah_iavg)
- / stepsize;
- uuc_reported = chip->last_uuc_uah - delta_uuc;
- } else {
- stepsize = max(uuc_min_step_size,
- uuc_multiplier * (last_soc - SOC_RBATT_DISCHG));
- if (uuc_uah_itest > uuc_uah_iavg) {
- if ((uuc_uah_iavg > uuc_uah_iavg_prev
- + UUC_IAVG_THRESHOLD_UAH)
- && chip->timer_uuc_expired)
- /*
- * there is a big jump in iavg current way past
- * the bootup increase uuc to this high iavg
- * based uuc in steps
- */
- delta_uuc = (uuc_uah_iavg - uuc_uah_iavg_prev)
- / uuc_iavg_div;
- else
- /* increase uuc towards itest based uuc */
- delta_uuc = (uuc_uah_itest - uuc_uah_iavg)
- / stepsize;
- } else {
- /*
- * the iavg based uuc was higher than itest based
- * uuc. This means that iavg > itest. Itest represents
- * the max current drawn from the device at anytime.
- * If we find iavg > itest, ignore iavg and simply step
- * up the uuc based on itest
- */
- delta_uuc = uuc_uah_itest / stepsize;
- }
- uuc_reported = min(uuc_uah_itest,
- chip->last_uuc_uah + delta_uuc);
- }
- pr_debug("uuc_prev = %d stepsize = %d d_uuc = %d uuc_reported = %d\n",
- chip->last_uuc_uah, (int)stepsize, delta_uuc,
- uuc_reported);
- return uuc_reported;
-}
-
+#define IAVG_SAMPLES 16
+#define CHARGING_IAVG_MA 300
static int calculate_unusable_charge_uah(struct pm8921_bms_chip *chip,
int rbatt, int fcc_uah, int cc_uah,
int soc_rbatt, int batt_temp, int chargecycles,
- int iavg_ua)
+ int iavg_ua, int delta_time_us)
{
- int uuc_uah_itest, uuc_uah_iavg, uuc_reported;
- static int firsttime = 1;
+ int uuc_uah_iavg;
+ int i;
int iavg_ma = iavg_ua / 1000;
+ static int iavg_samples[IAVG_SAMPLES];
+ static int iavg_index;
+ static int iavg_num_samples;
- /* calculate unusable charge with itest */
- uuc_uah_itest = calculate_uuc_uah_at_given_current(chip,
- batt_temp, chargecycles,
- rbatt, fcc_uah, chip->i_test);
+ if (delta_time_us == 0) {
+ /*
+ * this means uuc is being for the first time,
+ * iavg_ua will be 0 which will lead to unreasonably low uuc
+ * hence use the instantenous current instead of iavg_ua
+ * value for the first time
+ */
+ pm8921_bms_get_battery_current(&iavg_ua);
+ iavg_ma = iavg_ua / 1000;
+ }
- pr_debug("itest = %d uuc_itest = %d\n", chip->i_test, uuc_uah_itest);
+ /* if the time since last sample is small ignore it */
+ if (delta_time_us == 0 || delta_time_us > USEC_PER_SEC) {
+ /*
+ * if we are charging use a nominal avg current so that we keep
+ * a reasonable UUC while charging
+ */
+ if (iavg_ma < 0)
+ iavg_ma = CHARGING_IAVG_MA;
+ iavg_samples[iavg_index] = iavg_ma;
+ iavg_index = (iavg_index + 1) % IAVG_SAMPLES;
+ iavg_num_samples++;
+ if (iavg_num_samples >= IAVG_SAMPLES)
+ iavg_num_samples = IAVG_SAMPLES;
+ }
- /* calculate unusable charge with iavg */
- iavg_ma = max(0, iavg_ma);
+ /* now that this sample is added calcualte the average */
+ iavg_ma = 0;
+ if (iavg_num_samples != 0) {
+ for (i = 0; i < iavg_num_samples; i++) {
+ pr_debug("iavg_samples[%d] = %d\n", i, iavg_samples[i]);
+ iavg_ma += iavg_samples[i];
+ }
+
+ iavg_ma = DIV_ROUND_CLOSEST(iavg_ma, iavg_num_samples);
+ }
+
uuc_uah_iavg = calculate_uuc_uah_at_given_current(chip,
batt_temp, chargecycles,
rbatt, fcc_uah, iavg_ma);
pr_debug("iavg = %d uuc_iavg = %d\n", iavg_ma, uuc_uah_iavg);
- if (firsttime) {
- chip->uuc_uah_iavg_prev = uuc_uah_iavg;
-
- if (cc_uah < chip->last_cc_uah)
- chip->last_uuc_uah = uuc_uah_itest;
- else
- chip->last_uuc_uah = uuc_uah_iavg;
- pr_debug("firsttime uuc_prev = %d\n", chip->last_uuc_uah);
- }
-
- uuc_reported = scale_unusable_charge_uah(chip,
- cc_uah < chip->last_cc_uah,
- uuc_uah_iavg, uuc_uah_itest,
- chip->uuc_uah_iavg_prev);
-
- /* remember the last uuc_uah_iavg */
- chip->uuc_uah_iavg_prev = uuc_uah_iavg;
-
- /* remember the reported uuc */
- chip->last_uuc_uah = uuc_reported;
-
- if (firsttime == 1) {
- /* uuc calculation for the first time is done */
- firsttime = 0;
- }
-
- return uuc_reported;
+ return uuc_uah_iavg;
}
/* calculate remainging charge at the time of ocv */
@@ -1382,7 +1301,8 @@
*unusable_charge_uah = calculate_unusable_charge_uah(chip, *rbatt,
*fcc_uah, *cc_uah, soc_rbatt,
- batt_temp, chargecycles, *iavg_ua);
+ batt_temp, chargecycles, *iavg_ua,
+ *delta_time_us);
pr_debug("UUC = %uuAh\n", *unusable_charge_uah);
}
@@ -1486,10 +1406,15 @@
soc_est = bound_soc(soc_est);
/*
- * do not adjust if soc_est is between 45 and 25 OR soc_est is
- * same as what bms calculated
+ * do not adjust
+ * if soc is same as what bms calculated
+ * if soc_est is between 45 and 25, this is the flat portion of the
+ * curve where soc_est is not so accurate. We generally don't want to
+ * adjust when soc_est is inaccurate except for the cases when soc is
+ * way far off (higher than 50 or lesser than 20).
*/
- if (is_between(45, 25, soc_est) || soc_est == soc)
+ if (soc_est == soc
+ || (is_between(45, 25, soc_est) && is_between(50, 20, soc)))
goto out;
if (last_soc_est == -EINVAL)
@@ -2761,8 +2686,7 @@
mutex_init(&chip->last_ocv_uv_mutex);
chip->dev = &pdev->dev;
chip->r_sense = pdata->r_sense;
- chip->i_test = pdata->i_test;
- chip->v_failure = pdata->v_failure;
+ chip->v_cutoff = pdata->v_cutoff;
chip->max_voltage_uv = pdata->max_voltage_uv;
chip->batt_type = pdata->battery_type;
chip->rconn_mohm = pdata->rconn_mohm;
@@ -2829,10 +2753,6 @@
pm8921_bms_enable_irq(chip, PM8921_BMS_GOOD_OCV);
pm8921_bms_enable_irq(chip, PM8921_BMS_OCV_FOR_R);
- INIT_DELAYED_WORK(&chip->uuc_timer_work, uuc_timer_work);
- schedule_delayed_work(&chip->uuc_timer_work,
- msecs_to_jiffies(UUC_TIMER_MS));
-
get_battery_uvolts(chip, &vbatt);
pr_info("OK battery_capacity_at_boot=%d volt = %d ocv = %d\n",
pm8921_bms_get_percent_charge(),