Patch "usb: musb: Stop bulk endpoint while queue is rotated" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

usb: musb: Stop bulk endpoint while queue is rotated

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-musb-stop-bulk-endpoint-while-queue-is-rotated.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Andrew Goodbody <[email protected]>
Date: Tue, 31 May 2016 10:05:27 -0500
Subject: usb: musb: Stop bulk endpoint while queue is rotated

From: Andrew Goodbody <[email protected]>

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.

---
 drivers/usb/musb/musb_host.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

@@ -995,9 +995,15 @@ static void musb_bulk_nak_timeout(struct
 	if (is_in) {
 		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);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/usb-musb-stop-bulk-endpoint-while-queue-is-rotated.patch queue-4.4/usb-musb-ensure-rx-reinit-occurs-for-shared_fifo-endpoints.patch