xhci: Add support for endpoint soft reset

xhci supports soft retry recovery when the host halted the host side of an
endopint but the connected USB device is not aware of the halt.

In this case xhci needs to issue a reset endopint command  with a TSP
(Transfer State Preserve) flag set which preserves the Data toggle
and Sequence number of the endpoint.

This feature is needed to handle a few special transfer event types
such as USB Transaction error that don't always point to a causing TRB.

see xhci 4.6.8.1 for more details
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -1830,7 +1830,7 @@ static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
 	ep->ep_state |= EP_HALTED;
 	ep->stopped_stream = stream_id;
 
-	xhci_queue_reset_ep(xhci, command, slot_id, ep_index);
+	xhci_queue_reset_ep(xhci, command, slot_id, ep_index, EP_HARD_RESET);
 	xhci_cleanup_stalled_ring(xhci, ep_index, td);
 
 	ep->stopped_stream = 0;
@@ -4046,12 +4046,16 @@ void xhci_queue_new_dequeue_state(struct xhci_hcd *xhci,
 }
 
 int xhci_queue_reset_ep(struct xhci_hcd *xhci, struct xhci_command *cmd,
-			int slot_id, unsigned int ep_index)
+			int slot_id, unsigned int ep_index,
+			enum xhci_ep_reset_type reset_type)
 {
 	u32 trb_slot_id = SLOT_ID_FOR_TRB(slot_id);
 	u32 trb_ep_index = EP_ID_FOR_TRB(ep_index);
 	u32 type = TRB_TYPE(TRB_RESET_EP);
 
+	if (reset_type == EP_SOFT_RESET)
+		type |= TRB_TSP;
+
 	return queue_command(xhci, cmd, 0, 0, 0,
 			trb_slot_id | trb_ep_index | type, false);
 }

drivers/usb/host/xhci.h

@@ -1205,6 +1205,11 @@ struct xhci_event_cmd {
 /* Stop Ring - Transfer State Preserve */
 #define TRB_TSP		(1<<9)
 
+enum xhci_ep_reset_type {
+	EP_HARD_RESET,
+	EP_SOFT_RESET,
+};
+
 /* Force Event */
 #define TRB_TO_VF_INTR_TARGET(p)	(((p) & (0x3ff << 22)) >> 22)
 #define TRB_TO_VF_ID(p)			(((p) & (0xff << 16)) >> 16)
@@ -2040,7 +2045,8 @@ int xhci_queue_configure_endpoint(struct xhci_hcd *xhci,
 int xhci_queue_evaluate_context(struct xhci_hcd *xhci, struct xhci_command *cmd,
 		dma_addr_t in_ctx_ptr, u32 slot_id, bool command_must_succeed);
 int xhci_queue_reset_ep(struct xhci_hcd *xhci, struct xhci_command *cmd,
-		int slot_id, unsigned int ep_index);
+		int slot_id, unsigned int ep_index,
+		enum xhci_ep_reset_type reset_type);
 int xhci_queue_reset_device(struct xhci_hcd *xhci, struct xhci_command *cmd,
 		u32 slot_id);
 void xhci_find_new_dequeue_state(struct xhci_hcd *xhci,