usb: dwc3: workaround: bogus hibernation events

Revision 2.20a of the core has a known issue
which would generate bogus hibernation events
_and_ random failures on USB CV TD.9.23 test
case.

The suggested workaround is to ignore hibernation
events which don't match currently connected
speed.

Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 9e878d9bc909..7f4e6dd63c00 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2378,6 +2378,30 @@ static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
         dev_vdbg(dwc->dev, "%s link %d\n", __func__, dwc->link_state);
 }
 
+static void dwc3_gadget_hibernation_interrupt(struct dwc3 *dwc,
+                unsigned int evtinfo)
+{
+        unsigned int is_ss = evtinfo & BIT(4);
+
+        /**
+         * WORKAROUND: DWC3 revison 2.20a with hibernation support
+         * have a known issue which can cause USB CV TD.9.23 to fail
+         * randomly.
+         *
+         * Because of this issue, core could generate bogus hibernation
+         * events which SW needs to ignore.
+         *
+         * Refers to:
+         *
+         * STAR#9000546576: Device Mode Hibernation: Issue in USB 2.0
+         * Device Fallback from SuperSpeed
+         */
+        if (is_ss ^ (dwc->speed == USB_SPEED_SUPER))
+                return;
+
+        /* enter hibernation here */
+}
+
 static void dwc3_gadget_interrupt(struct dwc3 *dwc,
                 const struct dwc3_event_devt *event)
 {
@@ -2394,6 +2418,13 @@ static void dwc3_gadget_interrupt(struct dwc3 *dwc,
         case DWC3_DEVICE_EVENT_WAKEUP:
                 dwc3_gadget_wakeup_interrupt(dwc);
                 break;
+        case DWC3_DEVICE_EVENT_HIBER_REQ:
+                if (dev_WARN_ONCE(dwc->dev, !dwc->has_hibernation,
+                                        "unexpected hibernation event\n"))
+                        break;
+
+                dwc3_gadget_hibernation_interrupt(dwc, event->event_info);
+                break;
         case DWC3_DEVICE_EVENT_LINK_STATUS_CHANGE:
                 dwc3_gadget_linksts_change_interrupt(dwc, event->event_info);
                 break;