usb: dwc3: gadget: don't wrap around the TRB poll on non-ISOC

commit 8d62cd65d74d0e241b3a152f7347bb66126b705b upstream.

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.

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 064b6e2cd4118635508a1dcc4eddfd63e3d08189..9c134eb05beb484cf8f9492764d6442a43ef0aa5 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -667,6 +667,7 @@ 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);
@@ -674,6 +675,13 @@ 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 proceed requests then we are empty. Otherwise we ar