commit: 8d62cd65d74d0e241b3a152f7347bb66126b705b
From: Paul Zimmerman <[email protected]>
Date: Wed, 15 Feb 2012 13:35:06 +0200
Subject: usb: dwc3: gadget: don't wrap around the TRB poll on non-ISOC

If we have a non-ISOC endpoint, we will not have a Link TRB
pointing to the beginning of the TRB pool. On such endpoints,
we don't want to let the driver wrap around the TRB pool
otherwise controller will hang waiting for a valid TRB.

Cc: [email protected]
Signed-off-by: Paul Zimmerman <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>
---
 drivers/usb/dwc3/gadget.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index d121e73..48b2d0d 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -826,6 +826,7 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep, bool 
starting)
 {
        struct dwc3_request     *req, *n;
        u32                     trbs_left;
+       u32                     max;
        unsigned int            last_one = 0;
 
        BUILD_BUG_ON_NOT_POWER_OF_2(DWC3_TRB_NUM);
@@ -833,6 +834,13 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep, bool 
starting)
        /* the first request must not be queued */
        trbs_left = (dep->busy_slot - dep->free_slot) & DWC3_TRB_MASK;
 
+       /* Can't wrap around on a non-isoc EP since there's no link TRB */
+       if (!usb_endpoint_xfer_isoc(dep->desc)) {
+               max = DWC3_TRB_NUM - (dep->free_slot & DWC3_TRB_MASK);
+               if (trbs_left > max)
+                       trbs_left = max;
+       }
+
        /*
         * If busy & slot are equal than it is either full or empty. If we are
         * starting to process requests then we are empty. Otherwise we are
-- 
1.7.3.4
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