[PATCH v2] usb: dwc3: gadget: Move vbus draw to workqueue context

[Prashanth K <prashanth.k@oss.qualcomm.com>]

Currently dwc3_gadget_vbus_draw() can be called from atomic
context, which in turn invokes power-supply-core APIs. And
some these PMIC APIs have operations that may sleep, leading
to kernel panic.

Fix this by moving the vbus_draw into a workqueue context.

Fixes: 66e0ea341a2a ("usb: dwc3: core: Defer the probe until USB power supply ready")
Cc: stable@vger.kernel.org
Tested-by: Samuel Wu <wusamuel@google.com>
Signed-off-by: Prashanth K <prashanth.k@oss.qualcomm.com>
---
Changes in v2:
- Renamed vbus_draw_to_current limit, and rearranged the new variables.
- Link to v1: https://lore.kernel.org/all/20260129111403.3081730-1-prashanth.k@oss.qualcomm.com/

 drivers/usb/dwc3/core.c   | 19 ++++++++++++++++++-
 drivers/usb/dwc3/core.h   |  4 ++++
 drivers/usb/dwc3/gadget.c |  8 +++-----
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index f32b67bf73a4..cb5e829aaae8 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2155,6 +2155,20 @@ static int dwc3_get_num_ports(struct dwc3 *dwc)
 	return 0;
 }
 
+static void dwc3_vbus_draw_work(struct work_struct *work)
+{
+	struct dwc3 *dwc = container_of(work, struct dwc3, vbus_draw_work);
+	union power_supply_propval val = {0};
+	int ret;
+
+	val.intval = 1000 * (dwc->current_limit);
+	ret = power_supply_set_property(dwc->usb_psy, POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, &val);
+
+	if (ret < 0)
+		dev_dbg(dwc->dev, "Error (%d) setting vbus draw (%d mA)\n",
+			ret, dwc->current_limit);
+}
+
 static struct power_supply *dwc3_get_usb_power_supply(struct dwc3 *dwc)
 {
 	struct power_supply *usb_psy;
@@ -2169,6 +2183,7 @@ static struct power_supply *dwc3_get_usb_power_supply(struct dwc3 *dwc)
 	if (!usb_psy)
 		return ERR_PTR(-EPROBE_DEFER);
 
+	INIT_WORK(&dwc->vbus_draw_work, dwc3_vbus_draw_work);
 	return usb_psy;
 }
 
@@ -2395,8 +2410,10 @@ void dwc3_core_remove(struct dwc3 *dwc)
 
 	dwc3_free_event_buffers(dwc);
 
-	if (dwc->usb_psy)
+	if (dwc->usb_psy) {
+		cancel_work_sync(&dwc->vbus_draw_work);
 		power_supply_put(dwc->usb_psy);
+	}
 }
 EXPORT_SYMBOL_GPL(dwc3_core_remove);
 
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 08cc6f2b5c23..42cd1667a91b 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1058,6 +1058,8 @@ struct dwc3_glue_ops {
  * @role_switch_default_mode: default operation mode of controller while
  *			usb role is USB_ROLE_NONE.
  * @usb_psy: pointer to power supply interface.
+ * @vbus_draw_work: Work used for scheduling vbus_draw_work
+ * @current_limit: How much current to draw from vbus, in milliAmperes.
  * @usb2_phy: pointer to USB2 PHY
  * @usb3_phy: pointer to USB3 PHY
  * @usb2_generic_phy: pointer to array of USB2 PHYs
@@ -1244,6 +1246,8 @@ struct dwc3 {
 	enum usb_dr_mode	role_switch_default_mode;
 
 	struct power_supply	*usb_psy;
+	struct work_struct	vbus_draw_work;
+	unsigned int		current_limit;
 
 	u32			fladj;
 	u32			ref_clk_per;
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 9355c952c140..8562cc358694 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3124,8 +3124,6 @@ static void dwc3_gadget_set_ssp_rate(struct usb_gadget *g,
 static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
-	union power_supply_propval	val = {0};
-	int				ret;
 
 	if (dwc->usb2_phy)
 		return usb_phy_set_power(dwc->usb2_phy, mA);
@@ -3133,10 +3131,10 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 	if (!dwc->usb_psy)
 		return -EOPNOTSUPP;
 
-	val.intval = 1000 * mA;
-	ret = power_supply_set_property(dwc->usb_psy, POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, &val);
+	dwc->current_limit = mA;
+	schedule_work(&dwc->vbus_draw_work);
 
-	return ret;
+	return 0;
 }
 
 /**
-- 
2.34.1