[PATCH] power: supply: core: Honor supplied-from with CONFIG_OF=y

[Maurizio Casciano]

From: Maurizio Casciano <maurizio.casciano@xxxxxx>

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.

Move the generic supplied-from parser into an unconditional helper and try
it before firmware-reference power-supplies lookup. Keep an explicitly
supplied list at the highest priority and retain power-supplies as the
fallback. With the fix, ftrace shows the BQ25892 callback on hotplug and 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@xxxxxxxxxxxxxxx
Signed-off-by: Maurizio Casciano <maurizio.casciano@xxxxxx>
---
 drivers/power/supply/power_supply_core.c | 61 ++++++++++++++----------
 1 file changed, 36 insertions(+), 25 deletions(-)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 00d8bc98d588..5101decebb7a 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -190,6 +190,35 @@ static void power_supply_deferred_register_work(struct work_struct *work)
 		device_unlock(psy->dev.parent);
 }
 
+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;
+}
+
 #ifdef CONFIG_OF
 static int __power_supply_populate_supplied_from(struct power_supply *epsy,
 						 void *data)
@@ -262,19 +291,22 @@ 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 = 0, ret;
 
 	/* If there is already a list honor it */
 	if (psy->supplied_from && psy->num_supplies > 0)
 		return 0;
 
+	/* Check for the name-based "supplied-from" device property first. */
+	ret = power_supply_check_supplies_by_name(psy);
+	if (ret || psy->num_supplies)
+		return ret;
+
 	/* No device node found, nothing to do */
 	if (!psy->dev.fwnode)
 		return 0;
 
 	do {
-		int ret;
-
 		np = fwnode_find_reference(psy->dev.fwnode, "power-supplies", cnt++);
 		if (IS_ERR(np))
 			break;
@@ -304,28 +336,7 @@ static int power_supply_check_supplies(struct power_supply *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;
+	return power_supply_check_supplies_by_name(psy);
 }
 #endif
 
-- 
With Best Regards,
Maurizio Casciano