From: John Youn <johnyoun@synopsys.com>
Date: Fri, 20 May 2016 00:26:10 +0000 (-0700)
Subject: UPSTREAM: usb: dwc3: gadget: Don't prepare TRBs if no space
X-Git-Tag: firefly_0821_release~1803
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f906253bf08ba2aafbc0f6e907c580473e923bb2;p=firefly-linux-kernel-4.4.55.git

UPSTREAM: usb: dwc3: gadget: Don't prepare TRBs if no space

If trbs_left == 0, we don't have any space left in the TRB ring so don't
prepare anything.

Change-Id: I1dc6c665b778a7988fca9cd890884ad27dc830ef
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Wu Liang feng <wulf@rock-chips.com>
(cherry picked from commit 89bc856e5a7462e47d90d5a3f5396bd5795efd0c)
---

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index c690cb3d8918..a93b42973b97 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -942,6 +942,8 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep)
 	BUILD_BUG_ON_NOT_POWER_OF_2(DWC3_TRB_NUM);
 
 	trbs_left = dwc3_calc_trbs_left(dep);
+	if (!trbs_left)
+		return;
 
 	list_for_each_entry_safe(req, n, &dep->pending_list, list) {
 		if (req->request.num_mapped_sgs > 0)