linux-kernel - [PATCH] power: supply: max8903: configure USUS as output

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Date: Wed, 17 Apr 2024 15:35:00 +0200
From: Herman van Hazendonk <github.com@...rie.org>
To: Sebastian Reichel <sre@...nel.org>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ben Wolsieffer <benwolsieffer@...il.com>, 
 Herman van Hazendonk <github.com@...rie.org>
Subject: [PATCH] power: supply: max8903: configure USUS as output

The USUS pin was mistakenly configured as an input, when it should be an
output that specifies whether the USB power input is suspended. In addition
to fixing the pin mode, this patch also suspends the USB input when a DC
charger is connected, which should result in a slight reduction in USB
quiescent current.

Signed-off-by: Ben Wolsieffer <benwolsieffer@...il.com>
Signed-off-by: Herman van Hazendonk <github.com@...rie.org>
---
 drivers/power/supply/max8903_charger.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/max8903_charger.c b/drivers/power/supply/max8903_charger.c
index e65d0141f260..15dc3a5239e2 100644
--- a/drivers/power/supply/max8903_charger.c
+++ b/drivers/power/supply/max8903_charger.c
@@ -102,6 +102,10 @@ static irqreturn_t max8903_dcin(int irq, void *_data)
 	if (data->dcm)
 		gpiod_set_value(data->dcm, ta_in);
 
+	/* Set USB-Suspend 1:Suspended 0:Active */
+	if (data->usus)
+		gpiod_set_value(data->usus, ta_in);
+
 	/* Charger Enable / Disable */
 	if (data->cen) {
 		int val;
@@ -310,7 +314,15 @@ static int max8903_setup_gpios(struct platform_device *pdev)
 				     "failed to get FLT GPIO");
 	gpiod_set_consumer_name(data->flt, data->psy_desc.name);
 
-	data->usus = devm_gpiod_get_optional(dev, "usus", GPIOD_IN);
+	/*
+	 * Suspend the USB input if the DC charger is connected.
+	 *
+	 * The USUS line should be marked GPIO_ACTIVE_HIGH in the
+	 * device tree. Driving it low will enable the USB charger
+	 * input.
+	 */
+	flags = ta_in ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
+	data->usus = devm_gpiod_get_optional(dev, "usus", flags);
 	if (IS_ERR(data->usus))
 		return dev_err_probe(dev, PTR_ERR(data->usus),
 				     "failed to get USUS GPIO");

---
base-commit: 96fca68c4fbf77a8185eb10f7557e23352732ea2
change-id: 20240417-max8903-ace97d7d3407

Best regards,
-- 
Herman van Hazendonk <github.com@...rie.org>