linux-kernel - [PATCH V1 1/3] power: supply: sbs-battery: Fix false presence when registers read zero

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Message-ID: <20251229085636.4082852-1-Qing-wu.Li@leica-geosystems.com.cn>
Date: Mon, 29 Dec 2025 08:56:34 +0000
From: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
To: sre@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	linux-pm@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: bsp-development.geo@...ca-geosystems.com,
	LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
Subject: [PATCH V1 1/3] power: supply: sbs-battery: Fix false presence when registers read zero

Some platforms return zero for all SBS battery registers when the
battery is physically absent, instead of failing with an I2C error.
This causes the driver to incorrectly report the battery as present.

Add a sanity check: when the status register returns zero, also read
voltage and capacity. Only report the battery as present if at least
one of these is non-zero. This prevents false-positive detection on
systems where unpopulated battery slots return all-zero values.

Signed-off-by: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
---
 drivers/power/supply/sbs-battery.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
index 943c82ee978f..9537b692f9fd 100644
--- a/drivers/power/supply/sbs-battery.c
+++ b/drivers/power/supply/sbs-battery.c
@@ -594,9 +594,17 @@ static int sbs_get_battery_presence_and_health(
 		return ret;
 	}
 
-	if (psp == POWER_SUPPLY_PROP_PRESENT)
+	if (psp == POWER_SUPPLY_PROP_PRESENT) {
 		val->intval = 1; /* battery present */
-	else { /* POWER_SUPPLY_PROP_HEALTH */
+		if (ret == 0) {
+			int voltage = sbs_read_word_data(
+				client, sbs_data[REG_VOLTAGE].addr);
+			int capacity = sbs_read_word_data(
+				client, sbs_data[REG_CAPACITY].addr);
+			if ((voltage == 0) && (capacity == 0))
+				val->intval = 0;
+		}
+	} else { /* POWER_SUPPLY_PROP_HEALTH */
 		if (sbs_bat_needs_calibration(client)) {
 			val->intval = POWER_SUPPLY_HEALTH_CALIBRATION_REQUIRED;
 		} else {
-- 
2.43.0