xhci: Use soft retry to recover faster from transaction errors

Use soft retry to recover from a USB Transaction Errors that are caused by
temporary error conditions. The USB device is not aware that the xHC
has halted the endpoint, and will be waiting for another retry

A Soft Retry perform additional retries and recover from an error which has
caused the xHC to halt an endpoint.

Soft retry has some limitations:
Soft Retry attempts shall not be performed on Isoch endpoints
Soft Retry attempts shall not be performed if the device is behind a TT in
a HS Hub

Software shall limit the number of unsuccessful Soft Retry attempts to
prevent an infinite loop.

For more details on Soft retry see xhci specs  4.6.8.1
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -1155,6 +1155,10 @@ static void xhci_handle_cmd_reset_ep(struct xhci_hcd *xhci, int slot_id,
 		/* Clear our internal halted state */
 		xhci->devs[slot_id]->eps[ep_index].ep_state &= ~EP_HALTED;
 	}
+
+	/* if this was a soft reset, then restart */
+	if ((le32_to_cpu(trb->generic.field[3])) & TRB_TSP)
+		ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
 }
 
 static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci, int slot_id,
@@ -2132,10 +2136,16 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 	union xhci_trb *ep_trb, struct xhci_transfer_event *event,
 	struct xhci_virt_ep *ep, int *status)
 {
+	struct xhci_slot_ctx *slot_ctx;
 	struct xhci_ring *ep_ring;
 	u32 trb_comp_code;
 	u32 remaining, requested, ep_trb_len;
+	unsigned int slot_id;
+	int ep_index;
 
+	slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+	slot_ctx = xhci_get_slot_ctx(xhci, xhci->devs[slot_id]->out_ctx);
+	ep_index = TRB_TO_EP_ID(le32_to_cpu(event->flags)) - 1;
 	ep_ring = xhci_dma_to_transfer_ring(ep, le64_to_cpu(event->buffer));
 	trb_comp_code = GET_COMP_CODE(le32_to_cpu(event->transfer_len));
 	remaining = EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
@@ -2144,6 +2154,7 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 
 	switch (trb_comp_code) {
 	case COMP_SUCCESS:
+		ep_ring->err_count = 0;
 		/* handle success with untransferred data as short packet */
 		if (ep_trb != td->last_trb || remaining) {
 			xhci_warn(xhci, "WARN Successful completion on short TX\n");
@@ -2167,6 +2178,14 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 		ep_trb_len	= 0;
 		remaining	= 0;
 		break;
+	case COMP_USB_TRANSACTION_ERROR:
+		if ((ep_ring->err_count++ > MAX_SOFT_RETRY) ||
+		    le32_to_cpu(slot_ctx->tt_info) & TT_SLOT)
+			break;
+		*status = 0;
+		xhci_cleanup_halted_endpoint(xhci, slot_id, ep_index,
+					ep_ring->stream_id, td, EP_SOFT_RESET);
+		return 0;
 	default:
 		/* do nothing */
 		break;

drivers/usb/host/xhci.h

@@ -1496,6 +1496,7 @@ static inline const char *xhci_trb_type_string(u8 type)
 /* How much data is left before the 64KB boundary? */
 #define TRB_BUFF_LEN_UP_TO_BOUNDARY(addr)	(TRB_MAX_BUFF_SIZE - \
 					(addr & (TRB_MAX_BUFF_SIZE - 1)))
+#define MAX_SOFT_RETRY		3
 
 struct xhci_segment {
 	union xhci_trb		*trbs;
@@ -1583,6 +1584,7 @@ struct xhci_ring {
 	 * if we own the TRB (if we are the consumer).  See section 4.9.1.
 	 */
 	u32			cycle_state;
+	unsigned int            err_count;
 	unsigned int		stream_id;
 	unsigned int		num_segs;
 	unsigned int		num_trbs_free;