With SuperSpeed CDC NCM gadget, net2280 would get stuck in
'handle_ep_small' function. Triggering issue requires large
TCP transfer from host to USB3380.
Patch adds check for stuck condition and prevents hard lockup.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@xxxxxxxxxxx>
---
drivers/usb/gadget/udc/net2280.c | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
index 614ab951..cd876bf 100644
--- a/drivers/usb/gadget/udc/net2280.c
+++ b/drivers/usb/gadget/udc/net2280.c
@@ -1137,8 +1137,10 @@ dma_done(struct net2280_ep *ep, struct net2280_request *req, u32 dmacount,
done(ep, req, status);
}
-static void scan_dma_completions(struct net2280_ep *ep)
+static int scan_dma_completions(struct net2280_ep *ep)
{
+ int num_completed = 0;
+
/* only look at descriptors that were "naturally" retired,
* so fifo and list head state won't matter
*/
@@ -1166,6 +1168,7 @@ static void scan_dma_completions(struct net2280_ep *ep)
break;
/* single transfer mode */
dma_done(ep, req, tmp, 0);
+ num_completed++;
break;
} else if (!ep->is_in &&
(req->req.length % ep->ep.maxpacket) &&
@@ -1194,7 +1197,10 @@ static void scan_dma_completions(struct net2280_ep *ep)
}
}
dma_done(ep, req, tmp, 0);
+ num_completed++;
}
+
+ return num_completed;
}
static void restart_dma(struct net2280_ep *ep)
@@ -2547,8 +2553,11 @@ static void handle_ep_small(struct net2280_ep *ep)
/* manual DMA queue advance after short OUT */
if (likely(ep->dma)) {
if (t & BIT(SHORT_PACKET_TRANSFERRED_INTERRUPT)) {
- u32 count;
+ struct net2280_request *stuck_req = NULL;
int stopped = ep->stopped;
+ int num_completed;
+ int stuck = 0;
+ u32 count;
/* TRANSFERRED works around OUT_DONE erratum 0112.
* we expect (N <= maxpacket) bytes; host wrote M.
@@ -2560,7 +2569,7 @@ static void handle_ep_small(struct net2280_ep *ep)
/* any preceding dma transfers must finish.
* dma handles (M >= N), may empty the queue
*/
- scan_dma_completions(ep);
+ num_completed = scan_dma_completions(ep);
if (unlikely(list_empty(&ep->queue) ||
ep->out_overflow)) {
req = NULL;
@@ -2580,6 +2589,31 @@ static void handle_ep_small(struct net2280_ep *ep)
req = NULL;
break;
}
+
+ /* Escape loop if no dma transfers completed
+ * after few retries.
+ */
+ if (num_completed == 0) {
+ if (stuck_req == req &&
+ readl(&ep->dma->dmadesc) !=
+ req->td_dma && stuck++ > 5) {
+ count = readl(
+ &ep->dma->dmacount);
+ count &= DMA_BYTE_COUNT_MASK;
+ req = NULL;
+ ep_dbg(ep->dev, "%s escape stuck %d, count %u\n",
+ ep->ep.name, stuck,
+ count);
+ break;
+ } else if (stuck_req != req) {
+ stuck_req = req;
+ stuck = 0;
+ }
+ } else {
+ stuck_req = NULL;
+ stuck = 0;
+ }
+
udelay(1);
}
--
2.7.4
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