usb: dwc3: gadget: Skip checking Update Transfer status

If we're not setting CMDACT (from "No Response" Update Transfer
command), then there's no point in checking for the command status. So
skip it. This can reduce a register read delay and improve performance.
Signed-off-by: NThinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/3dc31cf11581ae3ee82d9202dda3fc17d897d786.1638240306.git.Thinh.Nguyen@synopsys.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/gadget.c

@@ -357,6 +357,12 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		cmd |= DWC3_DEPCMD_CMDACT;
 
 	dwc3_writel(dep->regs, DWC3_DEPCMD, cmd);
+
+	if (!(cmd & DWC3_DEPCMD_CMDACT)) {
+		ret = 0;
+		goto skip_status;
+	}
+
 	do {
 		reg = dwc3_readl(dep->regs, DWC3_DEPCMD);
 		if (!(reg & DWC3_DEPCMD_CMDACT)) {
@@ -398,6 +404,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		cmd_status = -ETIMEDOUT;
 	}
 
+skip_status:
 	trace_dwc3_gadget_ep_cmd(dep, cmd, params, cmd_status);
 
 	if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {