[PATCH v3] usb: cdnsp: fix issue with ZLP - added TD_SIZE = 1

[Pawel Laszczak <pawell@cadence.com>]

Patch modifies the TD_SIZE in TRB before ZLP TRB.
The TD_SIZE in TRB before ZLP TRB must be set to 1 to force
processing ZLP TRB by controller.

cc: <stable@vger.kernel.org>
Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
---
v2:
- returned value for last TRB must be 0
v3:
- fix issue for request->length > 64KB

 drivers/usb/cdns3/cdnsp-ring.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
index 794e413800ae..86e1141e150f 100644
--- a/drivers/usb/cdns3/cdnsp-ring.c
+++ b/drivers/usb/cdns3/cdnsp-ring.c
@@ -1763,10 +1763,15 @@ static u32 cdnsp_td_remainder(struct cdnsp_device *pdev,
 			      int trb_buff_len,
 			      unsigned int td_total_len,
 			      struct cdnsp_request *preq,
-			      bool more_trbs_coming)
+			      bool more_trbs_coming,
+			      bool zlp)
 {
 	u32 maxp, total_packet_count;
 
+	/* Before ZLP driver needs set TD_SIZE = 1. */
+	if (zlp)
+		return 1;
+
 	/* One TRB with a zero-length data packet. */
 	if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0) ||
 	    trb_buff_len == td_total_len)
@@ -1960,7 +1965,8 @@ int cdnsp_queue_bulk_tx(struct cdnsp_device *pdev, struct cdnsp_request *preq)
 		/* Set the TRB length, TD size, and interrupter fields. */
 		remainder = cdnsp_td_remainder(pdev, enqd_len, trb_buff_len,
 					       full_len, preq,
-					       more_trbs_coming);
+					       more_trbs_coming,
+					       zero_len_trb);
 
 		length_field = TRB_LEN(trb_buff_len) | TRB_TD_SIZE(remainder) |
 			TRB_INTR_TARGET(0);
@@ -2025,7 +2031,7 @@ int cdnsp_queue_ctrl_tx(struct cdnsp_device *pdev, struct cdnsp_request *preq)
 
 	if (preq->request.length > 0) {
 		remainder = cdnsp_td_remainder(pdev, 0, preq->request.length,
-					       preq->request.length, preq, 1);
+					       preq->request.length, preq, 1, 0);
 
 		length_field = TRB_LEN(preq->request.length) |
 				TRB_TD_SIZE(remainder) | TRB_INTR_TARGET(0);
@@ -2225,7 +2231,7 @@ static int cdnsp_queue_isoc_tx(struct cdnsp_device *pdev,
 		/* Set the TRB length, TD size, & interrupter fields. */
 		remainder = cdnsp_td_remainder(pdev, running_total,
 					       trb_buff_len, td_len, preq,
-					       more_trbs_coming);
+					       more_trbs_coming, 0);
 
 		length_field = TRB_LEN(trb_buff_len) | TRB_INTR_TARGET(0);
 
-- 
2.25.1