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Subject[PATCH 4.7 034/143] usb: dwc3: gadget: fix for short pkts during chained xfers
Date
4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felipe Balbi <felipe.balbi@linux.intel.com>

commit e5b36ae2f851024d43c76e51f395d32ce8d769ce upstream.

DWC3 has one interesting peculiarity with chained
transfers. If we setup N chained transfers and we
get a short packet before processing all N TRBs,
DWC3 will (conditionally) issue a XferComplete or
XferInProgress event and retire all TRBs from the
one which got a short packet to the last without
clearing their HWO bits.

This means SW must clear HWO bit manually, which
this patch is doing.

Cc: Brian E Rogers <brian.e.rogers@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/dwc3/gadget.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)

--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1897,7 +1897,8 @@ static void dwc3_gadget_free_endpoints(s

static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
struct dwc3_request *req, struct dwc3_trb *trb,
- const struct dwc3_event_depevt *event, int status)
+ const struct dwc3_event_depevt *event, int status,
+ int chain)
{
unsigned int count;
unsigned int s_pkt = 0;
@@ -1905,6 +1906,19 @@ static int __dwc3_cleanup_done_trbs(stru

trace_dwc3_complete_trb(dep, trb);

+ /*
+ * If we're in the middle of series of chained TRBs and we
+ * receive a short transfer along the way, DWC3 will skip
+ * through all TRBs including the last TRB in the chain (the
+ * where CHN bit is zero. DWC3 will also avoid clearing HWO
+ * bit and SW has to do it manually.
+ *
+ * We're going to do that here to avoid problems of HW trying
+ * to use bogus TRBs for transfers.
+ */
+ if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
+ trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
+
if ((trb->ctrl & DWC3_TRB_CTRL_HWO) && status != -ESHUTDOWN)
/*
* We continue despite the error. There is not much we
@@ -1916,6 +1930,7 @@ static int __dwc3_cleanup_done_trbs(stru
*/
dev_err(dwc->dev, "%s's TRB (%p) still owned by HW\n",
dep->name, trb);
+
count = trb->size & DWC3_TRB_SIZE_MASK;

if (dep->direction) {
@@ -1977,10 +1992,13 @@ static int dwc3_cleanup_done_reqs(struct
int ret;

do {
+ int chain;
+
req = next_request(&dep->started_list);
if (WARN_ON_ONCE(!req))
return 1;

+ chain = req->request.num_mapped_sgs > 0;
i = 0;
do {
slot = req->first_trb_index + i;
@@ -1990,9 +2008,8 @@ static int dwc3_cleanup_done_reqs(struct
trb = &dep->trb_pool[slot];
count += trb->size & DWC3_TRB_SIZE_MASK;

-
ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
- event, status);
+ event, status, chain);
if (ret)
break;
} while (++i < req->request.num_mapped_sgs);

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