linux-kernel - [PATCH 1/2] power: supply: Use the scope of power supplies to tell if power is system supplied

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Date:   Tue, 16 May 2023 13:25:40 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     <heikki.krogerus@...ux.intel.com>, <rafael@...nel.org>,
        <ajayg@...dia.com>, <andriy.shevchenko@...ux.intel.com>
CC:     <linux-i2c@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <Evan.Quan@....com>, <Lijo.Lazar@....com>,
        <Sanket.Goswami@....com>,
        "Mario Limonciello" <mario.limonciello@....com>
Subject: [PATCH 1/2] power: supply: Use the scope of power supplies to tell if power is system supplied

The logic used for power_supply_is_system_supplied() counts all power
supplies and:
* If no power supplies found assumes AC
* If non-battery power supplies found uses online to determine AC/DC.
  - If any are onlined, assumes AC
  - Othewise DC.

This logic makes sense for desktop systems that don't export an ACPI
battery, but it fails once you include a dGPU that provides a UCSI
power supply on a desktop system without any other power supplies.

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>
---
 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 ab986dbace16..d57f420ba8c3 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -348,6 +348,10 @@ 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,
@@ -366,8 +370,8 @@ 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;
-- 
2.34.1