Patch "usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize" has been added to the 3.18-stable tree

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 3.18-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-3.18 subdirectory.

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

From: "Felipe F. Tonello" <[email protected]>
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 <[email protected]>

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.

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

@@ -357,7 +357,9 @@ 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 [email protected] are

queue-3.18/usb-gadget-f_midi-fixed-a-bug-when-buflen-was-smaller-than-wmaxpacketsize.patch