From f073d10cd5a7b0b253de680de9e2b4a79057b039 Mon Sep 17 00:00:00 2001 From: Pawel Laszczak Date: Tue, 15 Nov 2022 05:00:39 -0500 Subject: [PATCH] usb: cdns3: remove fetched trb from cache before dequeuing 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: Signed-off-by: Pawel Laszczak Acked-by: Peter Chen Link: https://lore.kernel.org/r/20221115100039.441295-1-pawell@cadence.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/cdns3/cdns3-gadget.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c index 1802f68..924c279 100644 --- a/drivers/usb/cdns3/cdns3-gadget.c +++ b/drivers/usb/cdns3/cdns3-gadget.c @@ -2610,6 +2610,7 @@ 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; @@ -2645,6 +2646,13 @@ 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) | @@ -2656,6 +2664,10 @@ 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; -- 2.7.4