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usb: dwc3: gadget: always try to prepare on started_list first

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In cases where we're given an SG-list which is
longer than the amount of currently available TRBs,
we will be left with the same request on
started_list and we should prioritize that request
over possible new requests on pending_list. That's
a way to guarantee requests complete in order.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Felipe Balbi 2016-10-25 13:48:52 +03:00
parent e62c5bc573
commit d86c5a676e
1 changed files with 18 additions and 0 deletions
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18
drivers/usb/dwc3/gadget.c
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@ -1020,6 +1020,24 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep)
if (!dwc3_calc_trbs_left(dep))
return;
/*
* We can get in a situation where there's a request in the started list
* but there weren't enough TRBs to fully kick it in the first time
* around, so it has been waiting for more TRBs to be freed up.
*
* In that case, we should check if we have a request with pending_sgs
* in the started list and prepare TRBs for that request first,
* otherwise we will prepare TRBs completely out of order and that will
* break things.
*/
list_for_each_entry(req, &dep->started_list, list) {
if (req->num_pending_sgs > 0)
dwc3_prepare_one_trb_sg(dep, req);
if (!dwc3_calc_trbs_left(dep))
return;
}
list_for_each_entry_safe(req, n, &dep->pending_list, list) {
if (req->num_pending_sgs > 0)
dwc3_prepare_one_trb_sg(dep, req);