ab8500_fg: Overflow in current calculation

When calculating the average current the nominator will
overflow when the charging current is high.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Henrik Sölver <henrik.solver@stericsson.com>
Reviewed-by: Par-Olof HAKANSSON <par-olof.hakansson@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Tested-by: Par-Olof HAKANSSON <par-olof.hakansson@stericsson.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>

diff --git a/drivers/power/ab8500_fg.c b/drivers/power/ab8500_fg.c
index 2917def..570577c 100644 (file)
--- a/drivers/power/ab8500_fg.c
+++ b/drivers/power/ab8500_fg.c
@@ -805,12 +805,9 @@ static void ab8500_fg_acc_cur_work(struct work_struct *work)
 
        /*
         * Convert to unit value in mA
-        * Full scale input voltage is
-        * 66.660mV => LSB = 66.660mV/(4096*res) = 1.627mA
-        * Given a 250ms conversion cycle time the LSB corresponds
-        * to 112.9 nAh. Convert to current by dividing by the conversion
+        * by dividing by the conversion
         * time in hours (= samples / (3600 * 4)h)
-        * 112.9nAh assumes 10mOhm, but fg_res is in 0.1mOhm
+        * and multiply with 1000
         */
        di->avg_curr = (val * QLSB_NANO_AMP_HOURS_X10 * 36) /
                (1000 * di->bm->fg_res * (di->fg_samples / 4));
@@ -821,6 +818,8 @@ static void ab8500_fg_acc_cur_work(struct work_struct *work)
 
        queue_work(di->fg_wq, &di->fg_work);
 
+       dev_dbg(di->dev, "fg_res: %d, fg_samples: %d, gasg: %d, accu_charge: %d \n",
+                               di->bm->fg_res, di->fg_samples, val, di->accu_charge);
        return;
 exit:
        dev_err(di->dev,