From 5b43a2a84bac79fe8814949f5e173f83a5436c71 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Date: Thu, 23 Jul 2020 17:45:05 +0300
Subject: [PATCH] xhci: dbc: Don't use generic xhci inc_deq() function for dbc
Git-commit: 5b43a2a84bac79fe8814949f5e173f83a5436c71
References: jsc#SLE-14911
Patch-mainline: v5.9-rc1

The generic inc_deq() helper takes struct xhci_hcd pointer as a parameter,
and is a lot more complex than needed for the DbC usecase.

In order to decouple xhci and DbC we have to create our own small
inc_evt_deq() helper, not relying on xhci.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200723144530.9992-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/host/xhci-dbgcap.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index 987f893e941c..424b571d6ca9 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -644,6 +644,17 @@ static void dbc_handle_xfer_event(struct xhci_hcd *xhci, union xhci_trb *event)
 	xhci_dbc_giveback(req, status);
 }
 
+static void inc_evt_deq(struct xhci_ring *ring)
+{
+	/* If on the last TRB of the segment go back to the beginning */
+	if (ring->dequeue == &ring->deq_seg->trbs[TRBS_PER_SEGMENT - 1]) {
+		ring->cycle_state ^= 1;
+		ring->dequeue = ring->deq_seg->trbs;
+		return;
+	}
+	ring->dequeue++;
+}
+
 static enum evtreturn xhci_dbc_do_handle_events(struct xhci_dbc *dbc)
 {
 	dma_addr_t		deq;
@@ -765,7 +776,8 @@ static enum evtreturn xhci_dbc_do_handle_events(struct xhci_dbc *dbc)
 			break;
 		}
 
-		inc_deq(xhci, dbc->ring_evt);
+		inc_evt_deq(dbc->ring_evt);
+
 		evt = dbc->ring_evt->dequeue;
 		update_erdp = true;
 	}
-- 
2.26.2