xhci: xHCI 1.1: Stopped - Short Packet Capability (SPC)

This patch enables xhci driver to support SPC by handling
Stopped - Short Packet event in transfer event path.

If SPC = '1' and the stop endpoint command is executed, after a Short
Packet condition has been detected, but before the end of the TD has been
reached, (i.e. the TD is in progress for pipe), then a Transfer Event TRB
with its Completion Code set to Stopped - Short Packet and its TRB
Transfer Length set to value of the EDTLA shall be forced for the
interrupted TRB, irrespective of whether its IOC or ISP flags are set.
This Transfer Event TRB will precede the Command Completion Event TRB for
the command, and is referred to as a Stopped Transfer Event.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-dbg.c

@@ -101,6 +101,8 @@ static void xhci_print_cap_regs(struct xhci_hcd *xhci)
 			HCC_64BIT_ADDR(temp) ? "64" : "32");
 	xhci_dbg(xhci, "  HC %s Contiguous Frame ID Capability\n",
 			HCC_CFC(temp) ? "has" : "hasn't");
+	xhci_dbg(xhci, "  HC %s generate Stopped - Short Package event\n",
+			HCC_SPC(temp) ? "can" : "can't");
 	/* FIXME */
 	xhci_dbg(xhci, "  FIXME: more HCCPARAMS debugging\n");
 

drivers/usb/host/xhci-ring.c

@@ -1812,7 +1812,9 @@ static int finish_td(struct xhci_hcd *xhci, struct xhci_td *td,
 	if (skip)
 		goto td_cleanup;
 
-	if (trb_comp_code == COMP_STOP_INVAL || trb_comp_code == COMP_STOP) {
+	if (trb_comp_code == COMP_STOP_INVAL ||
+			trb_comp_code == COMP_STOP ||
+			trb_comp_code == COMP_STOP_SHORT) {
 		/* The Endpoint Stop Command completion will take care of any
 		 * stopped TDs.  A stopped TD may be restarted, so don't update
 		 * the ring dequeue pointer or take this TD off any lists yet.
@@ -1919,8 +1921,22 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
 		else
 			*status = 0;
 		break;
-	case COMP_STOP_INVAL:
+	case COMP_STOP_SHORT:
+		if (event_trb == ep_ring->dequeue || event_trb == td->last_trb)
+			xhci_warn(xhci, "WARN: Stopped Short Packet on ctrl setup or status TRB\n");
+		else
+			td->urb->actual_length =
+				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
+
+		return finish_td(xhci, td, event_trb, event, ep, status, false);
 	case COMP_STOP:
+		/* Did we stop at data stage? */
+		if (event_trb != ep_ring->dequeue && event_trb != td->last_trb)
+			td->urb->actual_length =
+				td->urb->transfer_buffer_length -
+				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
+		/* fall through */
+	case COMP_STOP_INVAL:
 		return finish_td(xhci, td, event_trb, event, ep, status, false);
 	default:
 		if (!xhci_requires_manual_halt_cleanup(xhci,
@@ -2014,6 +2030,8 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
 		}
 		if ((xhci->quirks & XHCI_TRUST_TX_LENGTH))
 			trb_comp_code = COMP_SHORT_TX;
+	/* fallthrough */
+	case COMP_STOP_SHORT:
 	case COMP_SHORT_TX:
 		frame->status = td->urb->transfer_flags & URB_SHORT_NOT_OK ?
 				-EREMOTEIO : 0;
@@ -2049,6 +2067,10 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
 	if (trb_comp_code == COMP_SUCCESS || skip_td) {
 		frame->actual_length = frame->length;
 		td->urb->actual_length += frame->length;
+	} else if (trb_comp_code == COMP_STOP_SHORT) {
+		frame->actual_length =
+			EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
+		td->urb->actual_length += frame->actual_length;
 	} else {
 		for (cur_trb = ep_ring->dequeue,
 		     cur_seg = ep_ring->deq_seg; cur_trb != event_trb;
@@ -2129,6 +2151,7 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 			*status = 0;
 		}
 		break;
+	case COMP_STOP_SHORT:
 	case COMP_SHORT_TX:
 		if (td->urb->transfer_flags & URB_SHORT_NOT_OK)
 			*status = -EREMOTEIO;
@@ -2145,8 +2168,20 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 				td->urb->ep->desc.bEndpointAddress,
 				td->urb->transfer_buffer_length,
 				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)));
+	/* Stopped - short packet completion */
+	if (trb_comp_code == COMP_STOP_SHORT) {
+		td->urb->actual_length =
+			EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
+
+		if (td->urb->transfer_buffer_length <
+				td->urb->actual_length) {
+			xhci_warn(xhci, "HC gave bad length of %d bytes txed\n",
+				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)));
+			td->urb->actual_length = 0;
+			 /* status will be set by usb core for canceled urbs */
+		}
 	/* Fast path - was this the last TRB in the TD for this URB? */
-	if (event_trb == td->last_trb) {
+	} else if (event_trb == td->last_trb) {
 		if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
 			td->urb->actual_length =
 				td->urb->transfer_buffer_length -
@@ -2300,6 +2335,9 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 	case COMP_STOP_INVAL:
 		xhci_dbg(xhci, "Stopped on No-op or Link TRB\n");
 		break;
+	case COMP_STOP_SHORT:
+		xhci_dbg(xhci, "Stopped with short packet transfer detected\n");
+		break;
 	case COMP_STALL:
 		xhci_dbg(xhci, "Stalled endpoint\n");
 		ep->ep_state |= EP_HALTED;

drivers/usb/host/xhci.h

@@ -119,6 +119,8 @@ struct xhci_cap_regs {
 #define HCC_LTC(p)		((p) & (1 << 6))
 /* true: no secondary Stream ID Support */
 #define HCC_NSS(p)		((p) & (1 << 7))
+/* true: HC supports Stopped - Short Packet */
+#define HCC_SPC(p)		((p) & (1 << 9))
 /* true: HC has Contiguous Frame ID Capability */
 #define HCC_CFC(p)		((p) & (1 << 11))
 /* Max size for Primary Stream Arrays - 2^(n+1), where n is bits 12:15 */
@@ -1063,8 +1065,8 @@ struct xhci_transfer_event {
 #define COMP_STOP	26
 /* Same as COMP_EP_STOPPED, but the transferred length in the event is invalid */
 #define COMP_STOP_INVAL	27
-/* Control Abort Error - Debug Capability - control pipe aborted */
-#define COMP_DBG_ABORT	28
+/* Same as COMP_EP_STOPPED, but a short packet detected */
+#define COMP_STOP_SHORT	28
 /* Max Exit Latency Too Large Error */
 #define COMP_MEL_ERR	29
 /* TRB type 30 reserved */