aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--drivers/usb/dwc3/ep0.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 39abc589187..69d5741a4db 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -174,6 +174,49 @@ static int __dwc3_gadget_ep0_queue(struct dwc3_ep *dep,
return 0;
}
+ /*
+ * Unfortunately we have uncovered a limitation wrt the Data Phase.
+ *
+ * Section 9.4 says we can wait for the XferNotReady(DATA) event to
+ * come before issueing Start Transfer command, but if we do, we will
+ * miss situations where the host starts another SETUP phase instead of
+ * the DATA phase. Such cases happen at least on TD.7.6 of the Link
+ * Layer Compliance Suite.
+ *
+ * The problem surfaces due to the fact that in case of back-to-back
+ * SETUP packets there will be no XferNotReady(DATA) generated and we
+ * will be stuck waiting for XferNotReady(DATA) forever.
+ *
+ * By looking at tables 9-13 and 9-14 of the Databook, we can see that
+ * it tells us to start Data Phase right away. It also mentions that if
+ * we receive a SETUP phase instead of the DATA phase, core will issue
+ * XferComplete for the DATA phase, before actually initiating it in
+ * the wire, with the TRB's status set to "SETUP_PENDING". Such status
+ * can only be used to print some debugging logs, as the core expects
+ * us to go through to the STATUS phase and start a CONTROL_STATUS TRB,
+ * just so it completes right away, without transferring anything and,
+ * only then, we can go back to the SETUP phase.
+ *
+ * Because of this scenario, SNPS decided to change the programming
+ * model of control transfers and support on-demand transfers only for
+ * the STATUS phase. To fix the issue we have now, we will always wait
+ * for gadget driver to queue the DATA phase's struct usb_request, then
+ * start it right away.
+ *
+ * If we're actually in a 2-stage transfer, we will wait for
+ * XferNotReady(STATUS).
+ */
+ if (dwc->three_stage_setup) {
+ unsigned direction;
+
+ direction = dwc->ep0_expect_in;
+ dwc->ep0state = EP0_DATA_PHASE;
+
+ __dwc3_ep0_do_control_data(dwc, dwc->eps[direction], req);
+
+ dep->flags &= ~DWC3_EP0_DIR_IN;
+ }
+
return 0;
}
@@ -707,6 +750,7 @@ static void dwc3_ep0_complete_data(struct dwc3 *dwc,
struct dwc3_trb *trb;
struct dwc3_ep *ep0;
u32 transferred;
+ u32 status;
u32 length;
u8 epnum;
@@ -719,6 +763,17 @@ static void dwc3_ep0_complete_data(struct dwc3 *dwc,
ur = &r->request;
trb = dwc->ep0_trb;
+
+ status = DWC3_TRB_SIZE_TRBSTS(trb->size);
+ if (status == DWC3_TRBSTS_SETUP_PENDING) {
+ dev_dbg(dwc->dev, "Setup Pending received\n");
+
+ if (r)
+ dwc3_gadget_giveback(ep0, r, -ECONNRESET);
+
+ return;
+ }
+
length = trb->size & DWC3_TRB_SIZE_MASK;
if (dwc->ep0_bounced) {
@@ -755,8 +810,11 @@ static void dwc3_ep0_complete_status(struct dwc3 *dwc,
{
struct dwc3_request *r;
struct dwc3_ep *dep;
+ struct dwc3_trb *trb;
+ u32 status;
dep = dwc->eps[0];
+ trb = dwc->ep0_trb;
if (!list_empty(&dep->request_list)) {
r = next_request(&dep->request_list);
@@ -776,6 +834,10 @@ static void dwc3_ep0_complete_status(struct dwc3 *dwc,
}
}
+ status = DWC3_TRB_SIZE_TRBSTS(trb->size);
+ if (status == DWC3_TRBSTS_SETUP_PENDING)
+ dev_dbg(dwc->dev, "Setup Pending received\n");
+
dwc->ep0state = EP0_SETUP_PHASE;
dwc3_ep0_out_start(dwc);
}