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authorFelipe Balbi2016-09-29 14:44:29 +0200
committerFelipe Balbi2016-10-17 10:14:00 +0200
commitd889c23ce4e3159e3d737f55f9d686a030a7ba87 (patch)
treef94ae828a487c92d7533b3d804e231eadc26afc1 /drivers/usb
parentusb: dwc3: gadget: properly account queued requests (diff)
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usb: dwc3: gadget: never pre-start Isochronous endpoints
We cannot pre-start isochronous endpoints because we rely on the micro-frame number passed via XferNotReady command for proper Isochronous scheduling. Fixes: 08a36b543803 ("usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()") Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/dwc3/gadget.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 3c3ced128c77..f15147f79d14 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1073,9 +1073,17 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
list_add_tail(&req->list, &dep->pending_list);
- if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
- dep->flags & DWC3_EP_PENDING_REQUEST) {
- if (list_empty(&dep->started_list)) {
+ /*
+ * NOTICE: Isochronous endpoints should NEVER be prestarted. We must
+ * wait for a XferNotReady event so we will know what's the current
+ * (micro-)frame number.
+ *
+ * Without this trick, we are very, very likely gonna get Bus Expiry
+ * errors which will force us issue EndTransfer command.
+ */
+ if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
+ if ((dep->flags & DWC3_EP_PENDING_REQUEST) &&
+ list_empty(&dep->started_list)) {
dwc3_stop_active_transfer(dwc, dep->number, true);
dep->flags = DWC3_EP_ENABLED;
}