linux-kernel - [PATCH v3 2/2] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

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Date:   Thu, 13 Aug 2020 13:10:08 +0800
From:   Ikjoon Jang <ikjn@...omium.org>
To:     Sebastian Reichel <sre@...nel.org>, linux-pm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, drinkcat@...omium.org,
        Ikjoon Jang <ikjn@...omium.org>
Subject: [PATCH v3 2/2] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

Current sbs-battery considers all smbus errors as disconnection events
when battery-detect pin isn't supplied, and restored to present state back
when any successful transaction is made.

This can lead to unlimited state changes between present and !present
when one unsupported command was requested and other following commands
were successful, e.g. udev rules tries to read multiple properties.

This patch checks battery presence by reading known good command to
check battery existence.

Signed-off-by: Ikjoon Jang <ikjn@...omium.org>
---
 drivers/power/supply/sbs-battery.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
index 6acb4ea25d2a..2e32fde04628 100644
--- a/drivers/power/supply/sbs-battery.c
+++ b/drivers/power/supply/sbs-battery.c
@@ -878,10 +878,17 @@ static int sbs_get_property(struct power_supply *psy,
 	if (!chip->enable_detection)
 		goto done;
 
-	if (!chip->gpio_detect &&
-		chip->is_present != (ret >= 0)) {
-		sbs_update_presence(chip, (ret >= 0));
-		power_supply_changed(chip->power_supply);
+	if (!chip->gpio_detect && chip->is_present != (ret >= 0)) {
+		bool old_present = chip->is_present;
+		union power_supply_propval val;
+
+		ret = sbs_get_battery_presence_and_health(
+				client, POWER_SUPPLY_PROP_PRESENT, &val);
+
+		sbs_update_presence(chip, !ret && val.intval);
+
+		if (old_present != chip->is_present)
+			power_supply_changed(chip->power_supply);
 	}
 
 done:
@@ -1067,11 +1074,13 @@ static int sbs_probe(struct i2c_client *client)
 	 * to the battery.
 	 */
 	if (!(force_load || chip->gpio_detect)) {
-		rc = sbs_read_word_data(client, sbs_data[REG_STATUS].addr);
+		union power_supply_propval val;
 
-		if (rc < 0) {
-			dev_err(&client->dev, "%s: Failed to get device status\n",
-				__func__);
+		rc = sbs_get_battery_presence_and_health(
+				client, POWER_SUPPLY_PROP_PRESENT, &val);
+		if (rc < 0 || !val.intval) {
+			dev_err(&client->dev, "Failed to get present status\n");
+			rc = -ENODEV;
 			goto exit_psupply;
 		}
 	}
-- 
2.28.0.236.gb10cc79966-goog