usb: musb: Stop bulk endpoint while queue is rotated

commit 7b2c17f829545df27a910e8d82e133c21c9a8c9c upstream.

Ensure that the endpoint is stopped by clearing REQPKT before
clearing DATAERR_NAKTIMEOUT before rotating the queue on the
dedicated bulk endpoint.
This addresses an issue where a race could result in the endpoint
receiving data before it was reprogrammed resulting in a warning
about such data from musb_rx_reinit before it was thrown away.
The data thrown away was a valid packet that had been correctly
ACKed which meant the host and device got out of sync.

Signed-off-by: Andrew Goodbody <andrew.goodbody@cambrionix.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index c655c71..f2b7268 100644 (file)
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -1384,9 +1384,15 @@ static void musb_bulk_rx_nak_timeout(struct musb *musb, struct musb_hw_ep *ep)
        musb_ep_select(mbase, ep->epnum);
        dma = is_dma_capable() ? ep->rx_channel : NULL;
 
-       /* clear nak timeout bit */
+       /*
+        * Need to stop the transaction by clearing REQPKT first
+        * then the NAK Timeout bit ref MUSBMHDRC USB 2.0 HIGH-SPEED
+        * DUAL-ROLE CONTROLLER Programmer's Guide, section 9.2.2
+        */
        rx_csr = musb_readw(epio, MUSB_RXCSR);
        rx_csr |= MUSB_RXCSR_H_WZC_BITS;
+       rx_csr &= ~MUSB_RXCSR_H_REQPKT;
+       musb_writew(epio, MUSB_RXCSR, rx_csr);
        rx_csr &= ~MUSB_RXCSR_DATAERROR;
        musb_writew(epio, MUSB_RXCSR, rx_csr);