[PATCH] usb: dwc2: Add safety check in setting of descriptor chain pointers

[Minas Harutyunyan]

In some MSC CV tests device sending ZLP IN on non EP0 which
reassigning EP0 OUT descriptor pointer to that EP.
Dedicated for EP0 OUT descriptor multiple time re-used by
other EP while that descriptor already in use by EP0 OUT
for SETUP transaction. As result when SETUP packet received
BNA interrupt asserting.

In dwc2_hsotg_program_zlp() function dwc2_gadget_set_ep0_desc_chain()
must be called only for EP0.

Signed-off-by: Minas Harutyunyan <hminas@xxxxxxxxxxxx>
---
 drivers/usb/dwc2/gadget.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 98a4a79e7f6e..3dc08f6847df 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -1943,7 +1943,9 @@ static void dwc2_hsotg_program_zlp(struct dwc2_hsotg *hsotg,
 		/* Not specific buffer needed for ep0 ZLP */
 		dma_addr_t dma = hs_ep->desc_list_dma;
 
-		dwc2_gadget_set_ep0_desc_chain(hsotg, hs_ep);
+		if (!index)
+			dwc2_gadget_set_ep0_desc_chain(hsotg, hs_ep);
+
 		dwc2_gadget_config_nonisoc_xfer_ddma(hs_ep, dma, 0);
 	} else {
 		dwc2_writel(DXEPTSIZ_MC(1) | DXEPTSIZ_PKTCNT(1) |
-- 
2.11.0