From:   Frank Li <Frank.Li@nxp.com>
To:     peter.chen@kernel.org, pawell@cadence.com
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        lznuaa@gmail.com
Subject: [PATCH 1/1] usb: cdns3: gadget: fix new urb never complete if ep cancel requests before.
Date:   Wed, 17 Nov 2021 14:44:47 -0600
Message-Id: <20211117204447.16869-1-Frank.Li@nxp.com>
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This issue was found at android12 MTP.
1. MTP submit many out urb request.
2. Cancel left requests (>20) when enough data get from host
3. Send ACK by IN endpoint.
4. MTP submit new out urb request.
5. 4's urb never complete.

TRACE LOG:

MtpServer-2157    [000] d..3  1287.150391: cdns3_ep_dequeue: ep1out: req: 00000000299e6836, req buff 000000009df42287, length: 0/16384 zsi, status: -115, trb: [start:87, end:87: virt addr 0x80004000ffd50420], flags:1 SID: 0
MtpServer-2157    [000] d..3  1287.150410: cdns3_gadget_giveback: ep1out: req: 00000000299e6836, req buff 000000009df42287, length: 0/16384 zsi, status: -104, trb: [start:87, end:87: virt addr 0x80004000ffd50420], flags:0 SID: 0
MtpServer-2157    [000] d..3  1287.150433: cdns3_ep_dequeue: ep1out: req: 0000000080b7bde6, req buff 000000009ed5c556, length: 0/16384 zsi, status: -115, trb: [start:88, end:88: virt addr 0x80004000ffd5042c], flags:1 SID: 0
MtpServer-2157    [000] d..3  1287.150446: cdns3_gadget_giveback: ep1out: req: 0000000080b7bde6, req buff 000000009ed5c556, length: 0/16384 zsi, status: -104, trb: [start:88, end:88: virt addr 0x80004000ffd5042c], flags:0 SID: 0
	....
MtpServer-2157    [000] d..1  1293.630410: cdns3_alloc_request: ep1out: req: 00000000afbccb7d, req buff 0000000000000000, length: 0/0 zsi, status: 0, trb: [start:0, end:0: virt addr (null)], flags:0 SID: 0
MtpServer-2157    [000] d..2  1293.630421: cdns3_ep_queue: ep1out: req: 00000000afbccb7d, req buff 00000000871caf90, length: 0/512 zsi, status: -115, trb: [start:0, end:0: virt addr (null)], flags:0 SID: 0
MtpServer-2157    [000] d..2  1293.630445: cdns3_wa1: WA1: ep1out set guard
MtpServer-2157    [000] d..2  1293.630450: cdns3_wa1: WA1: ep1out restore cycle bit
MtpServer-2157    [000] d..2  1293.630453: cdns3_prepare_trb: ep1out: trb 000000007317b3ee, dma buf: 0xffd5bc00, size: 512, burst: 128 ctrl: 0x00000424 (C=0, T=0, ISP, IOC, Normal) SID:0 LAST_SID:0
MtpServer-2157    [000] d..2  1293.630460: cdns3_doorbell_epx: ep1out, ep_trbaddr ffd50414
	....
irq/241-5b13000-2154    [000] d..1  1293.680849: cdns3_epx_irq: IRQ for ep1out: 01000408 ISP , ep_traddr: ffd508ac ep_last_sid: 00000000 use_streams: 0
irq/241-5b13000-2154    [000] d..1  1293.680858: cdns3_complete_trb: ep1out: trb 0000000021a11b54, dma buf: 0xffd50420, size: 16384, burst: 128 ctrl: 0x00001810 (C=0, T=0, CHAIN, LINK) SID:0 LAST_SID:0
irq/241-5b13000-2154    [000] d..1  1293.680865: cdns3_request_handled: Req: 00000000afbccb7d not handled, DMA pos: 185, ep deq: 88, ep enq: 185, start trb: 184, end trb: 184

Actually DMA pos already bigger than prevous submit request afbccb7d's TRB (184-184). The reason of (not handled) is that deq position is wrong.

The TRB link is below when irq happen.

	DEQ LINK LINK LINK LINK LINK .... TRB(afbccb7d):START  DMA(EP_TRADDR).

Original code check LINK TRB, but DEQ just move one step.

	LINK DEQ LINK LINK LINK LINK .... TRB(afbccb7d):START  DMA(EP_TRADDR).

This patch skip all LINK TRB and sync DEQ to trb's start.

	LINK LINK LINK LINK LINK .... DEQ = TRB(afbccb7d):START  DMA(EP_TRADDR).

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Jun Li <jun.li@nxp.com>
---
 drivers/usb/cdns3/cdns3-gadget.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 1f3b4a1422126..01d0e09a87ad7 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -337,17 +337,21 @@ static void cdns3_ep_inc_deq(struct cdns3_endpoint *priv_ep)
 	cdns3_ep_inc_trb(&priv_ep->dequeue, &priv_ep->ccs, priv_ep->num_trbs);
 }
 
-static void cdns3_move_deq_to_next_trb(struct cdns3_request *priv_req)
+static void cdns3_sync_deq_to_trb(struct cdns3_request *priv_req)
 {
 	struct cdns3_endpoint *priv_ep = priv_req->priv_ep;
-	int current_trb = priv_req->start_trb;
+	struct cdns3_trb *trb =  priv_ep->trb_pool + priv_ep->dequeue;
 
-	while (current_trb != priv_req->end_trb) {
-		cdns3_ep_inc_deq(priv_ep);
-		current_trb = priv_ep->dequeue;
-	}
+	if (TRB_FIELD_TO_TYPE(le32_to_cpu(trb->control)) == TRB_LINK) {
+		while (priv_ep->dequeue != priv_req->start_trb) {
+			dev_dbg(priv_ep->cdns3_dev->dev, "Remove TRB_LINK");
+			trb = priv_ep->trb_pool + priv_ep->dequeue;
+			WARN_ON_ONCE(TRB_FIELD_TO_TYPE(le32_to_cpu(trb->control)) != TRB_LINK);
+			trace_cdns3_complete_trb(priv_ep, trb);
 
-	cdns3_ep_inc_deq(priv_ep);
+			cdns3_ep_inc_deq(priv_ep);
+		}
+	}
 }
 
 /**
@@ -1518,10 +1522,7 @@ static void cdns3_transfer_completed(struct cdns3_device *priv_dev,
 		trb = priv_ep->trb_pool + priv_ep->dequeue;
 
 		/* Request was dequeued and TRB was changed to TRB_LINK. */
-		if (TRB_FIELD_TO_TYPE(le32_to_cpu(trb->control)) == TRB_LINK) {
-			trace_cdns3_complete_trb(priv_ep, trb);
-			cdns3_move_deq_to_next_trb(priv_req);
-		}
+		cdns3_sync_deq_to_trb(priv_req);
 
 		if (!request->stream_id) {
 			/* Re-select endpoint. It could be changed by other CPU
-- 
2.24.0.rc1