linux-kernel - [PATCH] power: supply: bq27xxx_battery: Do not return ENODEV when busy

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Message-ID: <20240913-foo-fix2-v1-1-a0f499404f3a@axis.com>
Date: Fri, 13 Sep 2024 16:45:37 +0800
From: Jerry Lv <Jerry.Lv@...s.com>
To: Pali Rohár <pali@...nel.org>, Sebastian Reichel
	<sre@...nel.org>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<kernel@...s.com>, Jerry Lv <Jerry.Lv@...s.com>
Subject: [PATCH] power: supply: bq27xxx_battery: Do not return ENODEV when
 busy

Multiple applications may access the device 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 gauge to update the properties is as expected.
The gauge typically recovers from busy state within a few milliseconds, and
the cached flag will not cause issues while updating the properties.

Signed-off-by: Jerry Lv <Jerry.Lv@...s.com>
---
 drivers/power/supply/bq27xxx_battery.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
index 750fda543308..eefbb5029a3b 100644
--- a/drivers/power/supply/bq27xxx_battery.c
+++ b/drivers/power/supply/bq27xxx_battery.c
@@ -2029,7 +2029,7 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
 		bq27xxx_battery_update_unlocked(di);
 	mutex_unlock(&di->lock);

-	if (psp != POWER_SUPPLY_PROP_PRESENT && di->cache.flags < 0)
+	if (psp != POWER_SUPPLY_PROP_PRESENT && di->cache.flags < 0 && di->cache.flags != -EBUSY)
 		return -ENODEV;

 	switch (psp) {

---
base-commit: da3ea35007d0af457a0afc87e84fddaebc4e0b63
change-id: 20240913-foo-fix2-a0d79db86a0b

Best regards,
-- 
Jerry Lv <Jerry.Lv@...s.com>