xhci: Support extended burst isoc TRB structure used by xhci 1.1 for USB 3.1

The transfer burst count (TBC) field in the Isoc TRB does not fit the new
larger burst count available for USB 3.1 SSP Isoc tranfers.
xhci 1.1 solved this by reusing the TD size field for transfer burst count.
The Mult field was outgrown as well. xhci 1.1  controllers can calculate
Mult itself and is not set if the new layout is used.

xhci 1.1 controllers that support the new Isoc TRB format expose a
Extended TBC Capability (ETC). To take the new format into use the xhci
host controller driver needs to set a Extended TBC Enable (ETE) bit.
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

@@ -3770,12 +3770,15 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		 * Prevent HW from getting the TRBs by keeping the cycle state
 		 * inverted in the first TDs isoc TRB.
 		 */
-		field = TRB_TBC(burst_count) |
-			TRB_TYPE(TRB_ISOC) |
+		field = TRB_TYPE(TRB_ISOC) |
 			TRB_TLBPC(last_burst_pkt_count) |
 			sia_frame_id |
 			(i ? ep_ring->cycle_state : !start_cycle);
 
+		/* xhci 1.1 with ETE uses TD_Size field for TBC, old is Rsvdz */
+		if (!xep->use_extended_tbc)
+			field |= TRB_TBC(burst_count);
+
 		/* fill the rest of the TRB fields, and remaining normal TRBs */
 		for (j = 0; j < trbs_per_td; j++) {
 			u32 remainder = 0;
@@ -3784,7 +3787,6 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			if (!first_trb)
 				field = TRB_TYPE(TRB_NORMAL) |
 					ep_ring->cycle_state;
-			first_trb = false;
 
 			/* Only set interrupt on short packet for IN EPs */
 			if (usb_urb_dir_in(urb))
@@ -3816,9 +3818,15 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 						   urb, trbs_per_td - j - 1);
 
 			length_field = TRB_LEN(trb_buff_len) |
-				TRB_TD_SIZE(remainder) |
 				TRB_INTR_TARGET(0);
 
+			/* xhci 1.1 with ETE uses TD Size field for TBC */
+			if (first_trb && xep->use_extended_tbc)
+				length_field |= TRB_TD_SIZE_TBC(burst_count);
+			else
+				length_field |= TRB_TD_SIZE(remainder);
+			first_trb = false;
+
 			queue_trb(xhci, ep_ring, more_trbs_coming,
 				lower_32_bits(addr),
 				upper_32_bits(addr),

drivers/usb/host/xhci.h

@@ -232,7 +232,9 @@ struct xhci_op_regs {
  * disabled, or powered-off state.
  */
 #define CMD_PM_INDEX	(1 << 11)
-/* bits 12:31 are reserved (and should be preserved on writes). */
+/* bit 14 Extended TBC Enable, changes Isoc TRB fields to support larger TBC */
+#define CMD_ETE		(1 << 14)
+/* bits 15:31 are reserved (and should be preserved on writes). */
 
 /* IMAN - Interrupt Management Register */
 #define IMAN_IE		(1 << 1)
@@ -943,6 +945,8 @@ struct xhci_virt_ep {
 	struct list_head	bw_endpoint_list;
 	/* Isoch Frame ID checking storage */
 	int			next_frame_id;
+	/* Use new Isoch TRB layout needed for extended TBC support */
+	bool			use_extended_tbc;
 };
 
 enum xhci_overhead_type {
@@ -1184,9 +1188,12 @@ enum xhci_setup_dev {
 #define	TRB_LEN(p)		((p) & 0x1ffff)
 /* TD Size, packets remaining in this TD, bits 21:17 (5 bits, so max 31) */
 #define TRB_TD_SIZE(p)          (min((p), (u32)31) << 17)
+/* xhci 1.1 uses the TD_SIZE field for TBC if Extended TBC is enabled (ETE) */
+#define TRB_TD_SIZE_TBC(p)      (min((p), (u32)31) << 17)
 /* Interrupter Target - which MSI-X vector to target the completion event at */
 #define TRB_INTR_TARGET(p)	(((p) & 0x3ff) << 22)
 #define GET_INTR_TARGET(p)	(((p) >> 22) & 0x3ff)
+/* Total burst count field, Rsvdz on xhci 1.1 with Extended TBC enabled (ETE) */
 #define TRB_TBC(p)		(((p) & 0x3) << 7)
 #define TRB_TLBPC(p)		(((p) & 0xf) << 16)