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

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Message-Id: <20200810070159.662863-1-ikjn@chromium.org>
Date:   Mon, 10 Aug 2020 15:01:59 +0800
From:   Ikjoon Jang <ikjn@...omium.org>
To:     Sebastian Reichel <sre@...nel.org>, linux-pm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Ikjoon Jang <ikjn@...omium.org>
Subject: [PATCH] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

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

This can leads 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 well-known register to
check battery existence.

Signed-off-by: Ikjoon Jang <ikjn@...omium.org>
---
 drivers/power/supply/sbs-battery.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
index 73461321eb05..483f814385a3 100644
--- a/drivers/power/supply/sbs-battery.c
+++ b/drivers/power/supply/sbs-battery.c
@@ -875,10 +875,17 @@ static int sbs_get_property(struct power_supply *psy,
 		return -EINVAL;
 	}
 
-	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:
@@ -1063,11 +1070,11 @@ 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);
-
-		if (rc < 0) {
-			dev_err(&client->dev, "%s: Failed to get device status\n",
-				__func__);
+		union power_supply_propval val;
+		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");
 			goto exit_psupply;
 		}
 	}
-- 
2.28.0.236.gb10cc79966-goog