usb: dwc3: gadget: Properly initialize LINK TRB

commit 1200a82a upstream.

On ISOC endpoints the last trb_pool entry used as a
LINK TRB is not getting zeroed out correctly due to
memset being called incorrectly and in the wrong place.
If pool allocated from DMA was not zero-initialized
to begin with this will result in the size and ctrl
values being random garbage. Call memset correctly after
assignment of the trb_link pointer.

Fixes: f6bafc6a ("usb: dwc3: convert TRBs into bitshifts")
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/usb/dwc3/gadget.c

@@ -615,12 +615,11 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep,
 		if (!usb_endpoint_xfer_isoc(desc))
 			return 0;
 
-		memset(&trb_link, 0, sizeof(trb_link));
-
 		/* Link TRB for ISOC. The HWO bit is never reset */
 		trb_st_hw = &dep->trb_pool[0];
 
 		trb_link = &dep->trb_pool[DWC3_TRB_NUM - 1];
+		memset(trb_link, 0, sizeof(*trb_link));
 
 		trb_link->bpl = lower_32_bits(dwc3_trb_dma_offset(dep, trb_st_hw));
 		trb_link->bph = upper_32_bits(dwc3_trb_dma_offset(dep, trb_st_hw));