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From:   Ikjoon Jang <ikjn@chromium.org>
To:     Sebastian Reichel <sre@kernel.org>, linux-pm@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, Ikjoon Jang <ikjn@chromium.org>
Subject: [PATCH v2 2/2] power: supply: sbs-battery: don't assume every i2c errors as battery disconnect
Date:   Tue, 11 Aug 2020 14:59:02 +0800
Message-Id: <20200811065902.2100551-1-ikjn@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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 known good command to
check battery existence.

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
---
v2: fix return value checking of sbs_get_battery_presence_and_health()
---
 drivers/power/supply/sbs-battery.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
index 6acb4ea25d2a..db964a470ebc 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;
+
+		sbs_get_battery_presence_and_health(
+				client, POWER_SUPPLY_PROP_PRESENT, &val);
+
+		sbs_update_presence(chip, val.intval);
+
+		if (old_present != chip->is_present)
+			power_supply_changed(chip->power_supply);
 	}
 
 done:
@@ -1067,11 +1074,12 @@ 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;
+		sbs_get_battery_presence_and_health(
+				client, POWER_SUPPLY_PROP_PRESENT, &val);
+		if (!val.intval) {
+			dev_err(&client->dev, "Failed to get present status\n");
+			rc = -ENODEV;
 			goto exit_psupply;
 		}
 	}
-- 
2.28.0.236.gb10cc79966-goog