usb: dwc3: avoid -Wmaybe-uninitialized warning

Cleaning up the loop in dwc3_cleanup_done_reqs() introduced a
gcc warning if built with "-Wmaybe-uninitialized":

drivers/usb/dwc3/gadget.c: In function 'dwc3_endpoint_transfer_complete':
drivers/usb/dwc3/gadget.c:2015:9: 'trb' may be used uninitialized in this function [-Wmaybe-uninitialized]

I believe it is a false positive and we always have a valid 'trb'
pointer at the end of the function, but neither I nor the compiler
are able to prove that.

This works around the warning by computing a flag earlier in the function
when it's guaranteed to be valid, which tells the compiler that it's
safe and makes it easier to understand to me.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 31162af447d7 ("usb: dwc3: gadget: avoid while (1) loop on completion")
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 37a86522fa88..a5d496dd53b2 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1934,6 +1934,7 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 {
         struct dwc3_request     *req, *n;
         struct dwc3_trb         *trb;
+        bool                    ioc = false;
         int                     ret;
 
         list_for_each_entry_safe(req, n, &dep->started_list, list) {
@@ -1981,8 +1982,12 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 
                 dwc3_gadget_giveback(dep, req, status);
 
-                if (ret)
+                if (ret) {
+                        if ((event->status & DEPEVT_STATUS_IOC) &&
+                            (trb->ctrl & DWC3_TRB_CTRL_IOC))
+                                ioc = true;
                         break;
+                }
         }
 
         /*
@@ -2010,10 +2015,9 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
                 return 1;
         }
 
-        if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
-                if ((event->status & DEPEVT_STATUS_IOC) &&
-                                (trb->ctrl & DWC3_TRB_CTRL_IOC))
-                        return 0;
+        if (usb_endpoint_xfer_isoc(dep->endpoint.desc) && ioc)
+                return 0;
+
         return 1;
 }