[PATCH 3/3] usb: chipidea: udc: make isoc endpoint a bit error tolerant

[Xu Yang <xu.yang_2@nxp.com>]

When a endpoint met errors, the usb controller will firstly assert
related error bit in status filed of dTD, then ENDPTCOMPLETE will be
asserted. Finally, USBSTS.UEI will be set.

Due to isoc transfers are error-tolerant transfers, we can make isoc
endpoint a bit error tolerant on device mode too. In case of error,
it's possilbe to resume the endpoint by reprime the corresponding
endpoint.

When error occurs, this will allow error dTD be deleted from dQH and
giveback request to user. Then, a reprime/prime operation is executed
depends on whether dQH is empty or not. If dQH is not empty, reprime
will be done during dequeue process. If dQH is empty, prime will be
done when new dTD is linked. In this way, isoc transfer can be recovered
from a small number of errors.

Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
---
 drivers/usb/chipidea/udc.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 0ab57b87b07b..b1a1be6439b6 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -683,6 +683,7 @@ static int _hardware_dequeue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 	unsigned remaining_length;
 	unsigned actual = hwreq->req.length;
 	struct ci_hdrc *ci = hwep->ci;
+	bool is_isoc = hwep->type == USB_ENDPOINT_XFER_ISOC;
 
 	if (hwreq->req.status != -EALREADY)
 		return -EINVAL;
@@ -696,7 +697,7 @@ static int _hardware_dequeue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 			int n = hw_ep_bit(hwep->num, hwep->dir);
 
 			if (ci->rev == CI_REVISION_24 ||
-			    ci->rev == CI_REVISION_22)
+			    ci->rev == CI_REVISION_22 || is_isoc)
 				if (!hw_read(ci, OP_ENDPTSTAT, BIT(n)))
 					reprime_dtd(ci, hwep, node);
 			hwreq->req.status = -EALREADY;
@@ -707,7 +708,6 @@ static int _hardware_dequeue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 		remaining_length >>= __ffs(TD_TOTAL_BYTES);
 		actual -= remaining_length;
 
-		hwreq->req.status = tmptoken & TD_STATUS;
 		if ((TD_STATUS_HALTED & hwreq->req.status)) {
 			hwreq->req.status = -EPIPE;
 			break;
@@ -715,11 +715,13 @@ static int _hardware_dequeue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 			hwreq->req.status = -EPROTO;
 			break;
 		} else if ((TD_STATUS_TR_ERR & hwreq->req.status)) {
-			hwreq->req.status = -EILSEQ;
-			break;
+			if (!is_isoc) {
+				hwreq->req.status = -EILSEQ;
+				break;
+			}
 		}
 
-		if (remaining_length) {
+		if (remaining_length && !is_isoc) {
 			if (hwep->dir == TX) {
 				hwreq->req.status = -EPROTO;
 				break;
-- 
2.34.1