usb: dwc3: workaround: missing disconnect event

DWC3 revisions <1.88a have an issue which would
case a missing Disconnect event if cable is
disconnected while there's a Setup packet
pending the FIFO.

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

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 6704a52c9f1..7c98b3f2e6a 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1640,6 +1640,7 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
 	dwc->start_config_issued = false;
 
 	dwc->gadget.speed = USB_SPEED_UNKNOWN;
+	dwc->setup_packet_pending = false;
 }
 
 static void dwc3_gadget_usb3_phy_power(struct dwc3 *dwc, int on)
@@ -1676,6 +1677,37 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
 
 	dev_vdbg(dwc->dev, "%s\n", __func__);
 
+	/*
+	 * WORKAROUND: DWC3 revisions <1.88a have an issue which
+	 * would cause a missing Disconnect Event if there's a
+	 * pending Setup Packet in the FIFO.
+	 *
+	 * There's no suggested workaround on the official Bug
+	 * report, which states that "unless the driver/application
+	 * is doing any special handling of a disconnect event,
+	 * there is no functional issue".
+	 *
+	 * Unfortunately, it turns out that we _do_ some special
+	 * handling of a disconnect event, namely complete all
+	 * pending transfers, notify gadget driver of the
+	 * disconnection, and so on.
+	 *
+	 * Our suggested workaround is to follow the Disconnect
+	 * Event steps here, instead, based on a setup_packet_pending
+	 * flag. Such flag gets set whenever we have a XferNotReady
+	 * event on EP0 and gets cleared on XferComplete for the
+	 * same endpoint.
+	 *
+	 * Refers to:
+	 *
+	 * STAR#9000466709: RTL: Device : Disconnect event not
+	 * generated if setup packet pending in FIFO
+	 */
+	if (dwc->revision < DWC3_REVISION_188A) {
+		if (dwc->setup_packet_pending)
+			dwc3_gadget_disconnect_interrupt(dwc);
+	}
+
 	/* Enable PHYs */
 	dwc3_gadget_usb2_phy_power(dwc, true);
 	dwc3_gadget_usb3_phy_power(dwc, true);