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path: root/drivers/usb/gadget/ci_udc.c
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Diffstat (limited to 'drivers/usb/gadget/ci_udc.c')
-rw-r--r--drivers/usb/gadget/ci_udc.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/usb/gadget/ci_udc.c b/drivers/usb/gadget/ci_udc.c
index 9cd0036..a68a85f 100644
--- a/drivers/usb/gadget/ci_udc.c
+++ b/drivers/usb/gadget/ci_udc.c
@@ -397,6 +397,21 @@ static int ci_ep_queue(struct usb_ep *ep,
num = ci_ep->desc->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
in = (ci_ep->desc->bEndpointAddress & USB_DIR_IN) != 0;
+ if (!num && ci_ep->req_primed) {
+ /*
+ * The flipping of ep0 between IN and OUT relies on
+ * ci_ep_queue consuming the current IN/OUT setting
+ * immediately. If this is deferred to a later point when the
+ * req is pulled out of ci_req->queue, then the IN/OUT setting
+ * may have been changed since the req was queued, and state
+ * will get out of sync. This condition doesn't occur today,
+ * but could if bugs were introduced later, and this error
+ * check will save a lot of debugging time.
+ */
+ printf("%s: ep0 transaction already in progress\n", __func__);
+ return -EPROTO;
+ }
+
ret = ci_bounce(ci_req, in);
if (ret)
return ret;