From 9be728dee090225e5a02e2e25ef2fca8036b45c5 Mon Sep 17 00:00:00 2001
From: Augustin Cavalier <waddlesplash@gmail.com>
Date: Sun, 16 Jun 2019 14:09:45 -0400
Subject: [PATCH] XHCI: Set the DCS bit in SetTRDequeue.

It is needed here as in ConfigureEndpoint. See inline comment.
This matches FreeBSD's behavior.
---
 src/add-ons/kernel/busses/usb/xhci.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/add-ons/kernel/busses/usb/xhci.cpp b/src/add-ons/kernel/busses/usb/xhci.cpp
index 554393d22e..9ade0634c6 100644
--- a/src/add-ons/kernel/busses/usb/xhci.cpp
+++ b/src/add-ons/kernel/busses/usb/xhci.cpp
@@ -2562,7 +2562,9 @@ XHCI::SetTRDequeue(uint64 dequeue, uint16 stream, uint8 endpoint, uint8 slot)
 {
 	TRACE("Set TR Dequeue\n");
 	xhci_trb trb;
-	trb.address = dequeue;
+	trb.address = dequeue | ENDPOINT_2_DCS_BIT;
+		// The DCS bit is copied from the address field as in ConfigureEndpoint.
+		// (XHCI 1.1 § 4.6.10 p142.)
 	trb.status = TRB_2_STREAM(stream);
 	trb.flags = TRB_3_TYPE(TRB_TYPE_SET_TR_DEQUEUE)
 		| TRB_3_SLOT(slot) | TRB_3_ENDPOINT(endpoint);