usb: xhci: Set 'Average TRB Length' to 8 for control endpoints

Update the codes to conform with xHCI spec chapter 6.2.3.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

drivers/usb/host/xhci-mem.c

@@ -850,6 +850,12 @@ void xhci_setup_addressable_virt_dev(struct xhci_ctrl *ctrl,
 	trb_64 = (uintptr_t)virt_dev->eps[0].ring->first_seg->trbs;
 	ep0_ctx->deq = cpu_to_le64(trb_64 | virt_dev->eps[0].ring->cycle_state);
 
+	/*
+	 * xHCI spec 6.2.3:
+	 * software shall set 'Average TRB Length' to 8 for control endpoints.
+	 */
+	ep0_ctx->tx_info = cpu_to_le32(EP_AVG_TRB_LENGTH(8));
+
 	/* Steps 7 and 8 were done in xhci_alloc_virt_device() */
 
 	xhci_flush_cache((uintptr_t)ep0_ctx, sizeof(struct xhci_ep_ctx));

drivers/usb/host/xhci.c

@@ -601,6 +601,12 @@ static int xhci_set_configuration(struct usb_device *udev)
 		ep_ctx[ep_index]->deq = cpu_to_le64(trb_64 |
 				virt_dev->eps[ep_index].ring->cycle_state);
 
+		/*
+		 * xHCI spec 6.2.3:
+		 * 'Average TRB Length' should be 8 for control endpoints.
+		 */
+		if (usb_endpoint_xfer_control(endpt_desc))
+			avg_trb_len = 8;
 		ep_ctx[ep_index]->tx_info =
 			cpu_to_le32(EP_MAX_ESIT_PAYLOAD_LO(max_esit_payload) |
 			EP_AVG_TRB_LENGTH(avg_trb_len));