FAILED: patch "[PATCH] usb: cdns3: remove fetched trb from cache before dequeuing" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Possible dependencies:

1301c7b9f7ef ("usb: cdns3: remove fetched trb from cache before dequeuing")
64b558f597d1 ("usb: cdns3: Change file names for cdns3 driver.")
118b2a3237cf ("usb: cdnsp: Add tracepoints for CDNSP driver")
3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
e93e58d27402 ("usb: cdnsp: Device side header file for CDNSP driver")
0b490046d8d7 ("usb: cdns3: Refactoring names in reusable code")
394c3a144de8 ("usb: cdns3: Moves reusable code to separate module")
f738957277ba ("usb: cdns3: Split core.c into cdns3-plat and core.c file")
db8892bb1bb6 ("usb: cdns3: Add support for DRD CDNSP")
d2a968dddf98 ("Merge tag 'usb-v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb into usb-next")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1301c7b9f7efad2f11ef924e317c18ebd714fc9a Mon Sep 17 00:00:00 2001
From: Pawel Laszczak <pawell@cadence.com>
Date: Tue, 15 Nov 2022 05:00:39 -0500
Subject: [PATCH] usb: cdns3: remove fetched trb from cache before dequeuing

After doorbell DMA fetches the TRB. If during dequeuing request
driver changes NORMAL TRB to LINK TRB but doesn't delete it from
controller cache then controller will handle cached TRB and packet
can be lost.

The example scenario for this issue looks like:
1. queue request - set doorbell
2. dequeue request
3. send OUT data packet from host
4. Device will accept this packet which is unexpected
5. queue new request - set doorbell
6. Device lost the expected packet.

By setting DFLUSH controller clears DRDY bit and stop DMA transfer.

Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
cc: <stable@vger.kernel.org>
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Acked-by: Peter Chen <peter.chen@kernel.org>
Link: https://lore.kernel.org/r/20221115100039.441295-1-pawell@cadence.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 5adcb349718c..ccfaebca6faa 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -2614,6 +2614,7 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
 	u8 req_on_hw_ring = 0;
 	unsigned long flags;
 	int ret = 0;
+	int val;
 
 	if (!ep || !request || !ep->desc)
 		return -EINVAL;
@@ -2649,6 +2650,13 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
 
 	/* Update ring only if removed request is on pending_req_list list */
 	if (req_on_hw_ring && link_trb) {
+		/* Stop DMA */
+		writel(EP_CMD_DFLUSH, &priv_dev->regs->ep_cmd);
+
+		/* wait for DFLUSH cleared */
+		readl_poll_timeout_atomic(&priv_dev->regs->ep_cmd, val,
+					  !(val & EP_CMD_DFLUSH), 1, 1000);
+
 		link_trb->buffer = cpu_to_le32(TRB_BUFFER(priv_ep->trb_pool_dma +
 			((priv_req->end_trb + 1) * TRB_SIZE)));
 		link_trb->control = cpu_to_le32((le32_to_cpu(link_trb->control) & TRB_CYCLE) |
@@ -2660,6 +2668,10 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
 
 	cdns3_gadget_giveback(priv_ep, priv_req, -ECONNRESET);
 
+	req = cdns3_next_request(&priv_ep->pending_req_list);
+	if (req)
+		cdns3_rearm_transfer(priv_ep, 1);
+
 not_found:
 	spin_unlock_irqrestore(&priv_dev->lock, flags);
 	return ret;