From fe8a6534396807b8a0863cd146b72c0bce0b0c88 Mon Sep 17 00:00:00 2001 From: Shawn Nematbakhsh Date: Tue, 13 Jun 2017 10:53:25 -0700 Subject: [PATCH] power: supply: sbs-battery: Prevent CAPACITY_MODE races A subset of smart battery commands return charge or energy depending on the CAPACITY_MODE bit setting of BatteryMode(). In order to unambiguously read a charge or energy value, it is necessary to ensure that CAPACITY_MODE is set as desired, and not changed for the duration of the attribute read. Signed-off-by: Shawn Nematbakhsh Reviewed-by: Guenter Roeck Signed-off-by: Sebastian Reichel --- drivers/power/supply/sbs-battery.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c index cf43e38..cdc1d71 100644 --- a/drivers/power/supply/sbs-battery.c +++ b/drivers/power/supply/sbs-battery.c @@ -171,6 +171,7 @@ struct sbs_info { u32 i2c_retry_count; u32 poll_retry_count; struct delayed_work work; + struct mutex mode_lock; }; static char model_name[I2C_SMBUS_BLOCK_MAX + 1]; @@ -622,7 +623,13 @@ static int sbs_get_property(struct power_supply *psy, if (ret < 0) break; + /* sbs_get_battery_capacity() will change the battery mode + * temporarily to read the requested attribute. Ensure we stay + * in the desired mode for the duration of the attribute read. + */ + mutex_lock(&chip->mode_lock); ret = sbs_get_battery_capacity(client, ret, psp, val); + mutex_unlock(&chip->mode_lock); break; case POWER_SUPPLY_PROP_SERIAL_NUMBER: @@ -807,6 +814,7 @@ static int sbs_probe(struct i2c_client *client, psy_cfg.of_node = client->dev.of_node; psy_cfg.drv_data = chip; chip->last_state = POWER_SUPPLY_STATUS_UNKNOWN; + mutex_init(&chip->mode_lock); /* use pdata if available, fall back to DT properties, * or hardcoded defaults if not -- 2.7.4