bq27000: report missing device better.

One an hdq buss, a missing device reads as 0xff, not -1.
So do a translation to allow detecting of a missing bus.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c
index a0f205b0471dd739105cd691c6099420306ec566..e10763e3a1d56f848f44b27b0b73134a11ec59fc 100644 (file)
--- a/drivers/power/bq27x00_battery.c
+++ b/drivers/power/bq27x00_battery.c
@@ -416,6 +416,9 @@ static void bq27x00_update(struct bq27x00_device_info *di)
        bool is_bq27425 = di->chip == BQ27425;
 
        cache.flags = bq27x00_read(di, BQ27x00_REG_FLAGS, !is_bq27500);
+       if ((cache.flags & 0xff) == 0xff)
+               /* read error */
+               cache.flags = -1;
        if (cache.flags >= 0) {
                if (!is_bq27500 && !is_bq27425
                                && (cache.flags & BQ27000_FLAG_CI)) {