On the bq27x00 and bq27x10 variants, a number of conditions can reset the
value stored in the NAC register. This will cause capacity, time-to-empty,
energy, and charge to report the value 0, even when the battery is full.
On the other hand, the chips provide a flag, EDVF, which reliably reports
the true battery empty condition, when these properties are really zero.
Therefore, discard readings for these properties if their value is 0 while
EDVF is unset.

Tested on the Nokia N900 with bq27200.

Signed-off-by: Sicelo A. Mhlongo <absicsz@???>
---
drivers/power/supply/bq27xxx_battery.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
index 2f31d750a4c1..29fc51653b5f 100644
--- a/drivers/power/supply/bq27xxx_battery.c
+++ b/drivers/power/supply/bq27xxx_battery.c
@@ -2147,6 +2147,10 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
         ret = bq27xxx_battery_current_and_status(di, val, NULL, NULL);
         break;
     case POWER_SUPPLY_PROP_CAPACITY:
+        /* If 0 is reported, it is expected that EDVF is also set */
+        if (!di->cache.capacity && di->opts & BQ27XXX_O_ZERO &&
+           !(di->cache.flags & BQ27000_FLAG_EDVF))
+            return -EINVAL;
         ret = bq27xxx_simple_value(di->cache.capacity, val);
         break;
     case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
@@ -2157,9 +2161,17 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
         break;
     case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
         ret = bq27xxx_battery_read_time(di, BQ27XXX_REG_TTE, val);
+        /* If 0 is reported, it is expected that EDVF is also set */
+        if (!ret && !val->intval && di->opts & BQ27XXX_O_ZERO &&
+           !(di->cache.flags & BQ27000_FLAG_EDVF))
+            return -EINVAL;
         break;
     case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
         ret = bq27xxx_battery_read_time(di, BQ27XXX_REG_TTECP, val);
+        /* If 0 is reported, it is expected that EDVF is also set */
+        if (!ret && !val->intval && di->opts & BQ27XXX_O_ZERO &&
+           !(di->cache.flags & BQ27000_FLAG_EDVF))
+            return -EINVAL;
         break;
     case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
         ret = bq27xxx_battery_read_time(di, BQ27XXX_REG_TTF, val);
@@ -2171,10 +2183,15 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
             val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
         break;
     case POWER_SUPPLY_PROP_CHARGE_NOW:
-        if (di->regs[BQ27XXX_REG_NAC] != INVALID_REG_ADDR)
+        if (di->regs[BQ27XXX_REG_NAC] != INVALID_REG_ADDR) {
             ret = bq27xxx_battery_read_nac(di, val);
-        else
+            /* If 0 is reported, it is expected that EDVF is also set */
+            if (!ret && !val->intval && di->opts & BQ27XXX_O_ZERO &&
+               !(di->cache.flags & BQ27000_FLAG_EDVF))
+                return -EINVAL;
+        } else {
             ret = bq27xxx_battery_read_rc(di, val);
+        }
         break;
     case POWER_SUPPLY_PROP_CHARGE_FULL:
         ret = bq27xxx_battery_read_fcc(di, val);
@@ -2199,6 +2216,10 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
         break;
     case POWER_SUPPLY_PROP_ENERGY_NOW:
         ret = bq27xxx_battery_read_energy(di, val);
+        /* If 0 is reported, it is expected that EDVF is also set */
+        if (!ret && !val->intval && di->opts & BQ27XXX_O_ZERO &&
+           !(di->cache.flags & BQ27000_FLAG_EDVF))
+            return -EINVAL;
         break;
     case POWER_SUPPLY_PROP_POWER_AVG:
         ret = bq27xxx_battery_pwr_avg(di, val);
-- 
2.47.2