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usb: dwc3: gadget: never pre-start Isochronous endpoints

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We cannot pre-start isochronous endpoints because we
rely on the micro-frame number passed via
XferNotReady command for proper Isochronous
scheduling.

Fixes: 08a36b5438 ("usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()")
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Felipe Balbi 2016-09-29 15:44:29 +03:00
parent a9c3ca5fae
commit d889c23ce4
1 changed files with 11 additions and 3 deletions
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14
drivers/usb/dwc3/gadget.c
View file

@ -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;
}