From ae423ef5d095e09970f52c08020fdbf7f9d87c22 Mon Sep 17 00:00:00 2001
From: Pawel Laszczak <pawell@cadence.com>
Date: Tue, 22 Nov 2022 03:51:38 -0500
Subject: [PATCH] usb: cdnsp: fix lack of ZLP for ep0
Git-commit: ae423ef5d095e09970f52c08020fdbf7f9d87c22
Patch-mainline: v6.2-rc1
References: git-fixes

Patch implements the handling of ZLP for control transfer.
To send the ZLP driver must prepare the extra TRB in TD with
length set to zero and TRB type to TRB_NORMAL.
The first TRB must have set TRB_CHAIN flag, TD_SIZE = 1
and TRB type to TRB_DATA.

Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
Cc: <stable@vger.kernel.org>
Reviewed-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Link: https://lore.kernel.org/r/20221122085138.332434-1-pawell@cadence.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/usb/cdns3/cdnsp-ring.c | 42 ++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
index 2f29431f612e..b23e543b3a3d 100644
--- a/drivers/usb/cdns3/cdnsp-ring.c
+++ b/drivers/usb/cdns3/cdnsp-ring.c
@@ -2006,10 +2006,11 @@ int cdnsp_queue_bulk_tx(struct cdnsp_device *pdev, struct cdnsp_request *preq)
 
 int cdnsp_queue_ctrl_tx(struct cdnsp_device *pdev, struct cdnsp_request *preq)
 {
-	u32 field, length_field, remainder;
+	u32 field, length_field, zlp = 0;
 	struct cdnsp_ep *pep = preq->pep;
 	struct cdnsp_ring *ep_ring;
 	int num_trbs;
+	u32 maxp;
 	int ret;
 
 	ep_ring = cdnsp_request_to_transfer_ring(pdev, preq);
@@ -2019,26 +2020,33 @@ int cdnsp_queue_ctrl_tx(struct cdnsp_device *pdev, struct cdnsp_request *preq)
 	/* 1 TRB for data, 1 for status */
 	num_trbs = (pdev->three_stage_setup) ? 2 : 1;
 
+	maxp = usb_endpoint_maxp(pep->endpoint.desc);
+
+	if (preq->request.zero && preq->request.length &&
+	    (preq->request.length % maxp == 0)) {
+		num_trbs++;
+		zlp = 1;
+	}
+
 	ret = cdnsp_prepare_transfer(pdev, preq, num_trbs);
 	if (ret)
 		return ret;
 
 	/* If there's data, queue data TRBs */
-	if (pdev->ep0_expect_in)
-		field = TRB_TYPE(TRB_DATA) | TRB_IOC;
-	else
-		field = TRB_ISP | TRB_TYPE(TRB_DATA) | TRB_IOC;
-
 	if (preq->request.length > 0) {
-		remainder = cdnsp_td_remainder(pdev, 0, preq->request.length,
-					       preq->request.length, preq, 1, 0);
+		field = TRB_TYPE(TRB_DATA);
 
-		length_field = TRB_LEN(preq->request.length) |
-				TRB_TD_SIZE(remainder) | TRB_INTR_TARGET(0);
+		if (zlp)
+			field |= TRB_CHAIN;
+		else
+			field |= TRB_IOC | (pdev->ep0_expect_in ? 0 : TRB_ISP);
 
 		if (pdev->ep0_expect_in)
 			field |= TRB_DIR_IN;
 
+		length_field = TRB_LEN(preq->request.length) |
+			       TRB_TD_SIZE(zlp) | TRB_INTR_TARGET(0);
+
 		cdnsp_queue_trb(pdev, ep_ring, true,
 				lower_32_bits(preq->request.dma),
 				upper_32_bits(preq->request.dma), length_field,
@@ -2046,6 +2054,20 @@ int cdnsp_queue_ctrl_tx(struct cdnsp_device *pdev, struct cdnsp_request *preq)
 				TRB_SETUPID(pdev->setup_id) |
 				pdev->setup_speed);
 
+		if (zlp) {
+			field = TRB_TYPE(TRB_NORMAL) | TRB_IOC;
+
+			if (!pdev->ep0_expect_in)
+				field = TRB_ISP;
+
+			cdnsp_queue_trb(pdev, ep_ring, true,
+					lower_32_bits(preq->request.dma),
+					upper_32_bits(preq->request.dma), 0,
+					field | ep_ring->cycle_state |
+					TRB_SETUPID(pdev->setup_id) |
+					pdev->setup_speed);
+		}
+
 		pdev->ep0_stage = CDNSP_DATA_STAGE;
 	}
 
-- 
2.35.3