[PATCH] 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
Signed-off-by: Prashanth K <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..c9af126b9695 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->vbus_draw_current);
+	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->vbus_draw_current);
+}
+
 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..052fb18c6b5c 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1178,6 +1178,8 @@ struct dwc3_glue_ops {
  * @wakeup_pending_funcs: Indicates whether any interface has requested for
  *			 function wakeup in bitmap format where bit position
  *			 represents interface_id.
+ * @vbus_draw_work: Workqueue used for scheduling vbus draw work
+ * @vbus_draw_current: How much current to draw from vbus, in milliAmperes.
  */
 struct dwc3 {
 	struct work_struct	drd_work;
@@ -1413,6 +1415,8 @@ struct dwc3 {
 	struct dentry		*debug_root;
 	u32			gsbuscfg0_reqinfo;
 	u32			wakeup_pending_funcs;
+	struct work_struct	vbus_draw_work;
+	unsigned int		vbus_draw_current;
 };
 
 #define INCRX_BURST_MODE 0
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 9355c952c140..03d8a3a151e0 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->vbus_draw_current = mA;
+	schedule_work(&dwc->vbus_draw_work);
 
-	return ret;
+	return 0;
 }
 
 /**
-- 
2.34.1