From: Pawel Laszczak pawell@cadence.com
commit 1301c7b9f7efad2f11ef924e317c18ebd714fc9a upstream.
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 --- drivers/usb/cdns3/cdns3-gadget.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
--- 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_e 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 @@ found:
/* 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 @@ found:
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;