linux-kernel - [PATCH v2 3/5] power: supply: axp20x_usb_power: fix race condition with usb bc

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Date: Tue, 30 Jan 2024 15:27:59 -0500
From: Aren Moynihan <aren@...cevolution.org>
To: linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Ondřej Jirman <megi@....cz>,
	Hans de Goede <j.w.r.degoede@...il.com>,
	Aidan MacDonald <aidanmacdonald.0x0@...il.com>,
	Aren Moynihan <aren@...cevolution.org>,
	Chen-Yu Tsai <wens@...e.org>,
	Sebastian Reichel <sre@...nel.org>
Subject: [PATCH v2 3/5] power: supply: axp20x_usb_power: fix race condition with usb bc

When input_current_limit is set while USB BC is in progress, the BC
module will overwrite the value that was set when it finishes detection.

Signed-off-by: Aren Moynihan <aren@...cevolution.org>
---

Changes in v2:
  - Split into sepereate commit, it was part of addig the input current
    limit before.

 drivers/power/supply/axp20x_usb_power.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/power/supply/axp20x_usb_power.c b/drivers/power/supply/axp20x_usb_power.c
index 923121b23d5f..ac5a3f126df6 100644
--- a/drivers/power/supply/axp20x_usb_power.c
+++ b/drivers/power/supply/axp20x_usb_power.c
@@ -117,6 +117,15 @@ static void axp20x_usb_power_poll_vbus(struct work_struct *work)
 	if (val != power->old_status)
 		power_supply_changed(power->supply);
 
+	if (power->usb_bc_en_bit && (val & AXP20X_PWR_STATUS_VBUS_PRESENT) !=
+		(power->old_status & AXP20X_PWR_STATUS_VBUS_PRESENT)) {
+		dev_dbg(power->dev, "Cable status changed, re-enabling USB BC");
+		ret = regmap_field_write(power->usb_bc_en_bit, 1);
+		if (ret)
+			dev_err(power->dev, "failed to enable USB BC: errno %d",
+				ret);
+	}
+
 	power->old_status = val;
 	power->online = val & AXP20X_PWR_STATUS_VBUS_USED;
 
@@ -265,12 +274,26 @@ static int axp20x_usb_power_set_voltage_min(struct axp20x_usb_power *power,
 static int axp20x_usb_power_set_input_current_limit(struct axp20x_usb_power *power,
 						    int intval)
 {
+	int ret;
 	unsigned int reg;
 	const unsigned int max = power->axp_data->curr_lim_table_size;
 
 	if (intval == -1)
 		return -EINVAL;
 
+	/*
+	 * BC1.2 detection can cause a race condition if we try to set a current
+	 * limit while it's in progress. When it finishes it will overwrite the
+	 * current limit we just set.
+	 */
+	if (power->usb_bc_en_bit) {
+		dev_dbg(power->dev,
+			"disabling BC1.2 detection because current limit was set");
+		ret = regmap_field_write(power->usb_bc_en_bit, 0);
+		if (ret)
+			return ret;
+	}
+
 	for (reg = max - 1; reg > 0; reg--)
 		if (power->axp_data->curr_lim_table[reg] <= intval)
 			break;
-- 
2.43.0