From a9f710fc7a2e0c71e9ad90f58aa0e176ad960275 Mon Sep 17 00:00:00 2001 From: Jerry Lv Date: Tue, 15 Apr 2025 11:40:47 +0800 Subject: [PATCH] power: supply: bq27xxx: Retrieve again when busy MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit f16d9fb6cf03fdbdefa41a8b32ba1e57afb7ae3d ] Multiple applications may access the battery gauge at the same time, so the gauge may be busy and EBUSY will be returned. The driver will set a flag to record the EBUSY state, and this flag will be kept until the next periodic update. When this flag is set, bq27xxx_battery_get_property() will just return ENODEV until the flag is updated. Even if the gauge was busy during the last accessing attempt, returning ENODEV is not ideal, and can cause confusion in the applications layer. Instead, retry accessing the I2C to update the flag is as expected, for the gauge typically recovers from busy state within a few milliseconds. If still failed to access the gauge, the real error code would be returned instead of ENODEV (as suggested by Pali Rohár). Reviewed-by: Pali Rohár Signed-off-by: Jerry Lv Link: https://lore.kernel.org/r/20250415-foo-fix-v2-1-5b45a395e4cc@axis.com Signed-off-by: Sebastian Reichel Signed-off-by: Sasha Levin --- drivers/power/supply/bq27xxx_battery.c | 2 +- drivers/power/supply/bq27xxx_battery_i2c.c | 13 ++++++++++++- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c index e6c4dfdc58c4..1cfec675f82f 100644 --- a/drivers/power/supply/bq27xxx_battery.c +++ b/drivers/power/supply/bq27xxx_battery.c @@ -1780,7 +1780,7 @@ static int bq27xxx_battery_get_property(struct power_supply *psy, mutex_unlock(&di->lock); if (psp != POWER_SUPPLY_PROP_PRESENT && di->cache.flags < 0) - return -ENODEV; + return di->cache.flags; switch (psp) { case POWER_SUPPLY_PROP_STATUS: diff --git a/drivers/power/supply/bq27xxx_battery_i2c.c b/drivers/power/supply/bq27xxx_battery_i2c.c index 08c7e2b4155a..bf235d0a9603 100644 --- a/drivers/power/supply/bq27xxx_battery_i2c.c +++ b/drivers/power/supply/bq27xxx_battery_i2c.c @@ -14,6 +14,7 @@ * GNU General Public License for more details. */ +#include #include #include #include @@ -40,6 +41,7 @@ static int bq27xxx_battery_i2c_read(struct bq27xxx_device_info *di, u8 reg, struct i2c_msg msg[2]; u8 data[2]; int ret; + int retry = 0; if (!client->adapter) return -ENODEV; @@ -56,7 +58,16 @@ static int bq27xxx_battery_i2c_read(struct bq27xxx_device_info *di, u8 reg, else msg[1].len = 2; - ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg)); + do { + ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg)); + if (ret == -EBUSY && ++retry < 3) { + /* sleep 10 milliseconds when busy */ + usleep_range(10000, 11000); + continue; + } + break; + } while (1); + if (ret < 0) return ret;