[PATCH 12/15] usb: xhci: Better error handling in abort_td()

[Ahmad Fatoum]

This ports U-Boot commit 2526cd993272966606cb64b1898343e6963fb1d9:

| Author:     Hector Martin <marcan at marcan.st>
| AuthorDate: Sun Oct 29 15:37:39 2023 +0900
|
| usb: xhci: Better error handling in abort_td()
|
| If the xHC has a problem with our STOP ENDPOINT command, it is likely to
| return a completion directly instead of first a transfer event for the
| in-progress transfer. Handle that more gracefully.
|
| We still BUG() on the error code, but at least we don't end up timing
| out on the event and ending up with unexpected event errors.
|
| Signed-off-by: Hector Martin <marcan at marcan.st>

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 drivers/usb/host/xhci-ring.c | 36 +++++++++++++++++++++++-------------
 drivers/usb/host/xhci.h      |  2 ++
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index d3f2018422cc..23357a882538 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -470,7 +470,8 @@ union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected,
 			continue;
 
 		type = TRB_FIELD_TO_TYPE(le32_to_cpu(event->event_cmd.flags));
-		if (type == expected)
+		if (type == expected ||
+		    (expected == TRB_NONE && type != TRB_PORT_STATUS))
 			return event;
 
 		if (type == TRB_PORT_STATUS)
@@ -549,29 +550,38 @@ static void abort_td(struct usb_device *udev, int ep_index)
 	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
 	struct xhci_ring *ring =  ctrl->devs[udev->slot_id]->eps[ep_index].ring;
 	union xhci_trb *event;
+	trb_type type;
 	dma_addr_t addr;
 	u32 field;
 
 	xhci_queue_command(ctrl, 0, udev->slot_id, ep_index, TRB_STOP_RING);
 
-	event = xhci_wait_for_event(ctrl, TRB_TRANSFER, XHCI_TIMEOUT_DEFAULT);
+	event = xhci_wait_for_event(ctrl, TRB_NONE, XHCI_TIMEOUT_DEFAULT);
 	if (!event)
 		return;
 
-	field = le32_to_cpu(event->trans_event.flags);
-	BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
-	BUG_ON(TRB_TO_EP_INDEX(field) != ep_index);
-	BUG_ON(GET_COMP_CODE(le32_to_cpu(event->trans_event.transfer_len
-		!= COMP_STOP)));
-	xhci_acknowledge_event(ctrl);
+	type = TRB_FIELD_TO_TYPE(le32_to_cpu(event->event_cmd.flags));
+	if (type == TRB_TRANSFER) {
+		field = le32_to_cpu(event->trans_event.flags);
+		BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
+		BUG_ON(TRB_TO_EP_INDEX(field) != ep_index);
+		BUG_ON(GET_COMP_CODE(le32_to_cpu(event->trans_event.transfer_len
+			!= COMP_STOP)));
+		xhci_acknowledge_event(ctrl);
 
-	event = xhci_wait_for_event(ctrl, TRB_COMPLETION, XHCI_TIMEOUT_DEFAULT);
-	if (!event)
-		return;
+		event = xhci_wait_for_event(ctrl, TRB_COMPLETION, XHCI_TIMEOUT_DEFAULT);
+		if (!event)
+			return;
+		type = TRB_FIELD_TO_TYPE(le32_to_cpu(event->event_cmd.flags));
 
-	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
+	} else {
+		dev_warn(ctrl->dev, "abort_td: Expected a TRB_TRANSFER TRB first\n");
+	}
+
+	BUG_ON(type != TRB_COMPLETION ||
+		TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
 		!= udev->slot_id || GET_COMP_CODE(le32_to_cpu(
-		event->event_cmd.status)) != COMP_SUCCESS);
+	        event->event_cmd.status)) != COMP_SUCCESS);
 	xhci_acknowledge_event(ctrl);
 
 	addr = xhci_trb_virt_to_dma(ring->enq_seg, ring->enqueue);
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 4a08f3f9e0d2..37e8cee843cf 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -906,6 +906,8 @@ union xhci_trb {
 
 /* TRB type IDs */
 typedef enum {
+	/* reserved, used as a software sentinel */
+	TRB_NONE = 0,
 	/* bulk, interrupt, isoc scatter/gather, and control data stage */
 	TRB_NORMAL = 1,
 	/* setup stage for control transfers */
-- 
2.39.2