The supplied-from device property is the name-based counterpart to
firmware-node power-supplies references. It was added for non-DT platforms,
but its parser is compiled only when CONFIG_OF is disabled. CONFIG_OF is
a global kernel option, so x86 systems commonly enable it even when
individual power supplies are described by software nodes.

Consequently, these consumers never populate supplied_from and supplier
notifications do not reach their external_power_changed() callbacks. On a
Lenovo Yoga Book YB1-X91L, ftrace showed the Whiskey Cove supplier
notification running without invoking the BQ25892 callback, leaving the
input current limit at its boot-time value.

Use a single power_supply_check_supplies() implementation for all
configurations. Preserve firmware-node power-supplies references as the
preferred firmware description and use the name-based supplied-from
property only when no references are specified. Continue to honor an
explicitly provided supplied_from list first and propagate errors from
specified firmware references.

With the fix, ftrace shows the BQ25892 callback on hotplug. A boot-offline
test changes its input current limit from 500 mA to 2 A.

Fixes: 58a36bb06891 ("power: supply: core: Add support for supplied-from device-property")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Maurizio Casciano <mauriziocasciano7@gmail.com>
---
Changes in v2:
- Keep firmware-node power-supplies references ahead of the name-based
  supplied-from fallback, as requested by Hans.
- Propagate errors while resolving specified firmware references.
- Use one power_supply_check_supplies() implementation, as requested by
  Sebastian.

Link: https://lore.kernel.org/r/20260901145156.3177187-1-mauriziocasciano7@gmail.com
---
 drivers/power/supply/power_supply_core.c | 84 ++++++++++++------------
 1 file changed, 42 insertions(+), 42 deletions(-)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 47e307709e5e..945052a8371e 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -190,7 +190,35 @@ static void power_supply_deferred_register_work(struct work_struct *work)
 		device_unlock(psy->dev.parent);
 }
 
-#ifdef CONFIG_OF
+static int power_supply_check_supplies_by_name(struct power_supply *psy)
+{
+	struct device *parent = psy->dev.parent;
+	int nval, ret;
+
+	if (!parent)
+		return 0;
+
+	nval = device_property_string_array_count(parent, "supplied-from");
+	if (nval <= 0)
+		return 0;
+
+	psy->supplied_from = devm_kmalloc_array(&psy->dev, nval,
+						sizeof(*psy->supplied_from),
+						GFP_KERNEL);
+	if (!psy->supplied_from)
+		return -ENOMEM;
+
+	ret = device_property_read_string_array(parent, "supplied-from",
+						(const char **)psy->supplied_from,
+						nval);
+	if (ret < 0)
+		return ret;
+
+	psy->num_supplies = nval;
+
+	return 0;
+}
+
 static int __power_supply_populate_supplied_from(struct power_supply *epsy,
 						 void *data)
 {
@@ -262,22 +290,21 @@ static int power_supply_find_supply_from_fwnode(struct fwnode_handle *supply_nod
 static int power_supply_check_supplies(struct power_supply *psy)
 {
 	struct fwnode_handle *np;
-	int cnt = 0;
+	int cnt, ret;
 
 	/* If there is already a list honor it */
 	if (psy->supplied_from && psy->num_supplies > 0)
 		return 0;
 
-	/* No device node found, nothing to do */
-	if (!psy->dev.fwnode)
-		return 0;
-
-	do {
-		int ret;
+	for (cnt = 0; psy->dev.fwnode; cnt++) {
+		np = fwnode_find_reference(psy->dev.fwnode, "power-supplies", cnt);
+		if (IS_ERR(np)) {
+			ret = PTR_ERR(np);
+			if (ret != -ENOENT)
+				return ret;
 
-		np = fwnode_find_reference(psy->dev.fwnode, "power-supplies", cnt++);
-		if (IS_ERR(np))
 			break;
+		}
 
 		ret = power_supply_find_supply_from_fwnode(np);
 		fwnode_handle_put(np);
@@ -286,48 +313,21 @@ static int power_supply_check_supplies(struct power_supply *psy)
 			dev_dbg(&psy->dev, "Failed to find supply!\n");
 			return ret;
 		}
-	} while (!IS_ERR(np));
+	}
 
-	/* Missing valid "power-supplies" entries */
-	if (cnt == 1)
-		return 0;
+	/* Fall back to the name-based property if no references were specified. */
+	if (!cnt)
+		return power_supply_check_supplies_by_name(psy);
 
 	/* All supplies found, allocate char * array for filling */
 	psy->supplied_from = devm_kcalloc(&psy->dev,
-					  cnt - 1, sizeof(*psy->supplied_from),
+					  cnt, sizeof(*psy->supplied_from),
 					  GFP_KERNEL);
 	if (!psy->supplied_from)
 		return -ENOMEM;
 
 	return power_supply_populate_supplied_from(psy);
 }
-#else
-static int power_supply_check_supplies(struct power_supply *psy)
-{
-	int nval, ret;
-
-	if (!psy->dev.parent)
-		return 0;
-
-	nval = device_property_string_array_count(psy->dev.parent, "supplied-from");
-	if (nval <= 0)
-		return 0;
-
-	psy->supplied_from = devm_kmalloc_array(&psy->dev, nval,
-						sizeof(char *), GFP_KERNEL);
-	if (!psy->supplied_from)
-		return -ENOMEM;
-
-	ret = device_property_read_string_array(psy->dev.parent,
-		"supplied-from", (const char **)psy->supplied_from, nval);
-	if (ret < 0)
-		return ret;
-
-	psy->num_supplies = nval;
-
-	return 0;
-}
-#endif
 
 struct psy_am_i_supplied_data {
 	struct power_supply *psy;
-- 
2.53.0