[3.13.y-ckt stable] Patch "usb: dwc3: gadget: Stop TRB preparation after limit is reached" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    usb: dwc3: gadget: Stop TRB preparation after limit is reached

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From de0dca67024a3f01878208fee6bc76d980ac3110 Mon Sep 17 00:00:00 2001
From: Amit Virdi <amit.virdi at st.com>
Date: Tue, 13 Jan 2015 14:27:21 +0530
Subject: usb: dwc3: gadget: Stop TRB preparation after limit is reached

commit 39e60635a01520e8c8ed3946a28c2b98e6a46f79 upstream.

DWC3 gadget sets up a pool of 32 TRBs for each EP during initialization. This
means, the max TRBs that can be submitted for an EP is fixed to 32. Since the
request queue for an EP is a linked list, any number of requests can be queued
to it by the gadget layer.  However, the dwc3 driver must not submit TRBs more
than the pool it has created for. This limit wasn't respected when SG was used
resulting in submitting more than the max TRBs, eventually leading to
non-transfer of the TRBs submitted over the max limit.

Root cause:
When SG is used, there are two loops iterating to prepare TRBs:
 - Outer loop over the request_list
 - Inner loop over the SG list
The code was missing break to get out of the outer loop.

Fixes: eeb720fb21d6 (usb: dwc3: gadget: add support for SG lists)
Signed-off-by: Amit Virdi <amit.virdi at st.com>
Signed-off-by: Felipe Balbi <balbi at ti.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/dwc3/gadget.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 71bff75..217cc175 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -905,6 +905,9 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep, bool starting)
 				if (last_one)
 					break;
 			}
+
+			if (last_one)
+				break;
 		} else {
 			dma = req->request.dma;
 			length = req->request.length;
--
1.9.1