usb: dwc3: gadget: Queue PM runtime idle on disconnect event

commit 3c7af52c7616c3aa6dacd2336ec748d4a65df8f4 upstream.

There is a scenario where DWC3 runtime suspend is blocked due to the
dwc->connected flag still being true while PM usage_count is zero after
DWC3 giveback is completed and the USB gadget session is being terminated.
This leads to a case where nothing schedules a PM runtime idle for the
device.

The exact condition is seen with the following sequence:
  1.  USB bus reset is issued by the host
  2.  Shortly after, or concurrently, a USB PD DR SWAP request is received
      (sink->source)
  3.  USB bus reset event handler runs and issues
      dwc3_stop_active_transfers(), and pending transfer are stopped
  4.  DWC3 usage_count decremented to 0, and runtime idle occurs while
      dwc->connected == true, returns -EBUSY
  5.  DWC3 disconnect event seen, dwc->connected set to false due to DR
      swap handling
  6.  No runtime idle after this point

Address this by issuing an asynchronous PM runtime idle call after the
disconnect event is completed, as it modifies the dwc->connected flag,
which is what blocks the initial runtime idle.

Fixes: fc8bb91bc83e ("usb: dwc3: implement runtime PM")
Cc:  <stable@vger.kernel.org>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20240103214946.2596-1-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 88d8d589f01484b296a47dfcacca88e71921e8e8..89de363ecf8bb125aed296e0c34614582a270e9b 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3983,6 +3983,13 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
        usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
 
        dwc3_ep0_reset_state(dwc);
+
+       /*
+        * Request PM idle to address condition where usage count is
+        * already decremented to zero, but waiting for the disconnect
+        * interrupt to set dwc->connected to FALSE.
+        */
+       pm_request_idle(dwc->dev);
 }
 
 static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)