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From 45bf78829065725fa73b4cacfaf2a2142056d301 Mon Sep 17 00:00:00 2001
From: Peter Chen <peter.chen@freescale.com>
Date: Sun, 1 Apr 2012 15:17:16 +0800
Subject: [PATCH 046/117] usb: gadget: fsl_udc_core: dTD's next dtd pointer
need to be updated once written
commit 4d0947dec4db1224354e2f6f00ae22ce38e62a43 upstream.
dTD's next dtd pointer need to be updated once CPU writes it, or this
request may not be handled by controller, then host will get NAK from
device forever.
This problem occurs when there is a request is handling, we need to add
a new request to dTD list, if this new request is added before the current
one is finished, the new request is intended to added as next dtd pointer
at current dTD, but without wmb(), the dTD's next dtd pointer may not be
updated when the controller reads it. In that case, the controller will
still get Terminate Bit is 1 at dTD's next dtd pointer, that means there is
no next request, then this new request is missed by controller.
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Acked-by: Li Yang <leoli@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/gadget/fsl_udc_core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/usb/gadget/fsl_udc_core.c b/drivers/usb/gadget/fsl_udc_core.c
index 9085d14..185db03 100644
--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c
@@ -736,6 +736,8 @@ static void fsl_queue_td(struct fsl_ep *ep, struct fsl_req *req)
lastreq = list_entry(ep->queue.prev, struct fsl_req, queue);
lastreq->tail->next_td_ptr =
cpu_to_hc32(req->head->td_dma & DTD_ADDR_MASK);
+ /* Ensure dTD's next dtd pointer to be updated */
+ wmb();
/* Read prime bit, if 1 goto done */
if (fsl_readl(&dr_regs->endpointprime) & bitmask)
return;
--
1.7.9.5
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