usb: musb: mediatek: add reset FADDR to zero in reset interrupt handle

When receiving reset interrupt, FADDR need to be reset to zero in
peripheral mode. Otherwise ep0 cannot do enumeration when re-plugging USB
cable.
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Acked-by: Min Guo <min.guo@mediatek.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200525025049.3400-5-b-liu@ti.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/mediatek.c

@@ -208,6 +208,12 @@ static irqreturn_t generic_interrupt(int irq, void *__hci)
 	musb->int_rx = musb_clearw(musb->mregs, MUSB_INTRRX);
 	musb->int_tx = musb_clearw(musb->mregs, MUSB_INTRTX);
 
+	if ((musb->int_usb & MUSB_INTR_RESET) && !is_host_active(musb)) {
+		/* ep0 FADDR must be 0 when (re)entering peripheral mode */
+		musb_ep_select(musb->mregs, 0);
+		musb_writeb(musb->mregs, MUSB_FADDR, 0);
+	}
+
 	if (musb->int_usb || musb->int_tx || musb->int_rx)
 		retval = musb_interrupt(musb);