power: supply: bq27xxx: Retrieve again when busy

[ 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 <pali@kernel.org>
Signed-off-by: Jerry Lv <Jerry.Lv@axis.com>
Link: https://lore.kernel.org/r/20250415-foo-fix-v2-1-5b45a395e4cc@axis.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
index be2aac8fbf43064251ce1a779b3e991d79bdb06d..b8131f823654d27d6d4cd2e7b5be8ded4574ad10 100644 (file)
--- a/drivers/power/supply/bq27xxx_battery.c
+++ b/drivers/power/supply/bq27xxx_battery.c
@@ -2000,7 +2000,7 @@ 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 6fbae8fc2e501c41b8de4dbdea4a85beefe5ca34..d0c8edadec4bcf929f32c0b608cb02a0a7042760 100644 (file)
--- a/drivers/power/supply/bq27xxx_battery_i2c.c
+++ b/drivers/power/supply/bq27xxx_battery_i2c.c
@@ -6,6 +6,7 @@
  *     Andrew F. Davis <afd@ti.com>
  */
 
+#include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
@@ -32,6 +33,7 @@ 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;
@@ -48,7 +50,16 @@ 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;