[PATCH v3 8/9] usb: dwc3: core: Prevent otg events from disabling themselves

[Roger Quadros <rogerq@ti.com>]

There is a race happening during dwc3_drd_init() that causes
otg events to get disabled. This is what happens.

dwc3_otg_irq() happens immediately when PRTCAP is set to OTG,
even though OEVTEN is 0. This is because BIT 31 IRQ of
OEVT can't be disabled by OEVTEN.
We configure OEVTEN in dwc3_otg_init() but dwc3_otg_irq() has
already saved OEVTEN as 0 into dwc->oevten. So finally when
dwc3_irq_thread_irq() is called we save 0 into OEVTEN
thus disabling OTG irqs forever.

We fix this by disabling IRQs when configuring OEVTEN in
dwc3_otg_init().

Signed-off-by: Roger Quadros <rogerq@ti.com>
---
 drivers/usb/dwc3/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index d050e0e..e3c094d 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -905,6 +905,7 @@ static int dwc3_drd_init(struct dwc3 *dwc)
 	int ret, id, vbus;
 	u32 reg;
 	struct dwc3_hwparams *parms = &dwc->hwparams;
+	unsigned long flags;
 
 	/* If extcon device is not present we rely on OTG core for ID event */
 	if (!dwc->edev) {
@@ -982,6 +983,8 @@ try_otg_core:
 		goto error;
 	}
 
+	spin_lock_irqsave(&dwc->lock, flags);
+
 	/* we need to set OTG to get events from OTG core */
 	dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
 	/* GUSB2PHYCFG0.SusPHY=0 */
@@ -1007,6 +1010,8 @@ try_otg_core:
 	/* OCTL.PeriMode = 1 */
 	dwc3_writel(dwc->regs, DWC3_OCTL, DWC3_OCTL_PERIMODE);
 
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
 	dwc3_otg_fsm_sync(dwc);
 	usb_otg_sync_inputs(dwc->fsm);
 
-- 
2.1.4