linux-kernel - [PATCH AUTOSEL 4.19 07/13] power: supply: Fix logic checking if system is running from battery

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Date:   Wed, 31 May 2023 09:45:35 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mario Limonciello <mario.limonciello@....com>,
        Evan Quan <Evan.Quan@....com>, Lijo Lazar <Lijo.Lazar@....com>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        Sasha Levin <sashal@...nel.org>, sre@...nel.org,
        linux-pm@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 07/13] power: supply: Fix logic checking if system is running from battery

From: Mario Limonciello <mario.limonciello@....com>

[ Upstream commit 95339f40a8b652b5b1773def31e63fc53c26378a ]

The logic used for power_supply_is_system_supplied() counts all power
supplies and assumes that the system is running from AC if there is
either a non-battery power-supply reporting to be online or if no
power-supplies exist at all.

The second rule is for desktop systems, that don't have any
battery/charger devices. These systems will incorrectly report to be
powered from battery once a device scope power-supply is registered
(e.g. a HID device), since these power-supplies increase the counter.

Apart from HID devices, recent dGPUs provide UCSI power supplies on a
desktop systems. The dGPU by default doesn't have anything plugged in so
it's 'offline'. This makes power_supply_is_system_supplied() return 0
with a count of 1 meaning all drivers that use this get a wrong judgement.

To fix this case adjust the logic to also examine the scope of the power
supply. If the power supply is deemed a device power supply, then don't
count it.

Cc: Evan Quan <Evan.Quan@....com>
Suggested-by: Lijo Lazar <Lijo.Lazar@....com>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/power/supply/power_supply_core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 9b98921a3b16a..1d1a095569e91 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -350,6 +350,10 @@ static int __power_supply_is_system_supplied(struct device *dev, void *data)
 	struct power_supply *psy = dev_get_drvdata(dev);
 	unsigned int *count = data;

+	if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_SCOPE, &ret))
+		if (ret.intval == POWER_SUPPLY_SCOPE_DEVICE)
+			return 0;
+
 	(*count)++;
 	if (psy->desc->type != POWER_SUPPLY_TYPE_BATTERY)
 		if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_ONLINE,
@@ -368,8 +372,8 @@ int power_supply_is_system_supplied(void)
 				      __power_supply_is_system_supplied);

 	/*
-	 * If no power class device was found at all, most probably we are
-	 * running on a desktop system, so assume we are on mains power.
+	 * If no system scope power class device was found at all, most probably we
+	 * are running on a desktop system, so assume we are on mains power.
 	 */
 	if (count == 0)
 		return 1;
-- 
2.39.2