Patch "usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize

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-gadget-f_midi-fixed-a-bug-when-buflen-was-smaller-than-wmaxpacketsize.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 <stable@vger.kernel.org> know about it.


>From 03d27ade4941076b34c823d63d91dc895731a595 Mon Sep 17 00:00:00 2001
From: "Felipe F. Tonello" <eu@felipetonello.com>
Date: Wed, 9 Mar 2016 19:39:30 +0000
Subject: usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize

From: Felipe F. Tonello <eu@felipetonello.com>

commit 03d27ade4941076b34c823d63d91dc895731a595 upstream.

buflen by default (256) is smaller than wMaxPacketSize (512) in high-speed
devices.

That caused the OUT endpoint to freeze if the host send any data packet of
length greater than 256 bytes.

This is an example dump of what happended on that enpoint:
HOST:   [DATA][Length=260][...]
DEVICE: [NAK]
HOST:   [PING]
DEVICE: [NAK]
HOST:   [PING]
DEVICE: [NAK]
...
HOST:   [PING]
DEVICE: [NAK]

This patch fixes this problem by setting the minimum usb_request's buffer size
for the OUT endpoint as its wMaxPacketSize.

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/gadget/function/f_midi.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -361,7 +361,9 @@ static int f_midi_set_alt(struct usb_fun
 	/* allocate a bunch of read buffers and queue them all at once. */
 	for (i = 0; i < midi->qlen && err == 0; i++) {
 		struct usb_request *req =
-			midi_alloc_ep_req(midi->out_ep, midi->buflen);
+			midi_alloc_ep_req(midi->out_ep,
+				max_t(unsigned, midi->buflen,
+					bulk_out_desc.wMaxPacketSize));
 		if (req == NULL)
 			return -ENOMEM;
 


Patches currently in stable-queue which might be from eu@felipetonello.com are

queue-4.4/usb-gadget-f_midi-fixed-a-bug-when-buflen-was-smaller-than-wmaxpacketsize.patch