[PATCH v2] power/supply: ingenic-battery: Don't change scale if there's only one

[Paul Cercueil]

The ADC in the JZ4740 can work either in high-precision mode with a 2.5V
range, or in low-precision mode with a 7.5V range. The code in place in
this driver will select the proper scale according to the maximum
voltage of the battery.

The JZ4770 however only has one mode, with a 6.6V range. If only one
scale is available, there's no need to change it (and nothing to change
it to), and trying to do so will fail with -EINVAL.

Fixes: fb24ccfbe1e0 ("power: supply: add Ingenic JZ47xx battery driver.")

Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---

Notes:
    v2: Rebased on v5.4-rc7

 drivers/power/supply/ingenic-battery.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/power/supply/ingenic-battery.c b/drivers/power/supply/ingenic-battery.c
index 35816d4b3012..5a53057b4f64 100644
--- a/drivers/power/supply/ingenic-battery.c
+++ b/drivers/power/supply/ingenic-battery.c
@@ -80,6 +80,10 @@ static int ingenic_battery_set_scale(struct ingenic_battery *bat)
 	if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2)
 		return -EINVAL;
 
+	/* Only one (fractional) entry - nothing to change */
+	if (scale_len == 2)
+		return 0;
+
 	max_mV = bat->info.voltage_max_design_uv / 1000;
 
 	for (i = 0; i < scale_len; i += 2) {
-- 
2.24.0