[PATCH v2] usb: dwc3: Prevent indefinite sleep in _dwc3_set_mode during suspend/resume

From: Roger Quadros
Date: Fri Mar 09 2018 - 07:47:15 EST


In the following test we get stuck by sleeping forever in _dwc3_set_mode()
after which dual-role switching doesn't work.

On dra7-evm's dual-role port,
- Load g_zero gadget driver and enumerate to host
- suspend to mem
- disconnect USB cable to host and connect otg cable with Pen drive in it.
- resume system
- we sleep indefinitely in _dwc3_set_mode due to.
dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->
dwc3_gadget_stop()->wait_event_lock_irq()

To fix this instead of waiting indefinitely with wait_event_lock_irq()
we use wait_event_interruptible_lock_irq_timeout() and print
and error message if there was a timeout.

Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---

Changelog:

v2:
- use wait_event_interruptible_lock_irq_timeout() instead of wait_event_lock_irq()

drivers/usb/dwc3/gadget.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 2bda4eb..7c3a6e4 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1950,6 +1950,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
struct dwc3 *dwc = gadget_to_dwc(g);
unsigned long flags;
int epnum;
+ u32 tmo_eps = 0;

spin_lock_irqsave(&dwc->lock, flags);

@@ -1960,6 +1961,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)

for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
struct dwc3_ep *dep = dwc->eps[epnum];
+ int ret;

if (!dep)
continue;
@@ -1967,9 +1969,24 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
continue;

- wait_event_lock_irq(dep->wait_end_transfer,
- !(dep->flags & DWC3_EP_END_TRANSFER_PENDING),
- dwc->lock);
+ ret = wait_event_interruptible_lock_irq_timeout(dep->wait_end_transfer,
+ !(dep->flags & DWC3_EP_END_TRANSFER_PENDING),
+ dwc->lock, msecs_to_jiffies(5));
+
+ if (ret <= 0) {
+ /* Timed out or interrupted! There's nothing much
+ * we can do so we just log here and print which
+ * endpoints timed out at the end.
+ */
+ tmo_eps |= 1 << epnum;
+ dep->flags &= DWC3_EP_END_TRANSFER_PENDING;
+ }
+ }
+
+ if (tmo_eps) {
+ dev_err(dwc->dev,
+ "end transfer timed out on endpoints 0x%x [bitmap]\n",
+ tmo_eps);
}

out:
--
cheers,
-roger

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