usb: xhci-mtk: fix random remote wakeup

Some platforms, e.g. 8183/8192, use low level latch way to keep
wakeup signal, it may latch a wrong signal if debounce more time,
and enable wakeup function earlier.
____________________
ip_sleep ____/ \_____________
___________________
wakeup_signal ____________/ \______
_______________________________
wakeup_en _______/
^ ^
|(1) |(2)
latch wakeup_signal mistakenly at (1), should latch it at (2);

Workaround: delay about 100us to enable wakeup, meanwhile decrease
debounce time.

Signed-off-by: Chunfeng Yun <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/xhci-mtk.c

···
 	/* wait for host ip to sleep */
 	ret = readl_poll_timeout(&ippc->ip_pw_sts1, value,
 			  (value & STS1_IP_SLEEP_STS), 100, 100000);
-	if (ret) {
+	if (ret)
 		dev_err(mtk->dev, "ip sleep failed!!!\n");
-		return ret;
-	}
-	return 0;
+	else /* workaound for platforms using low level latch */
+		usleep_range(100, 200);
+
+	return ret;
 }
 
 static int xhci_mtk_ssusb_config(struct xhci_hcd_mtk *mtk)
···
 	case SSUSB_UWK_V1_1:
 		reg = mtk->uwk_reg_base + PERI_WK_CTRL0;
 		msk = WC0_IS_EN | WC0_IS_C(0xf) | WC0_IS_P;
-		val = enable ? (WC0_IS_EN | WC0_IS_C(0x8)) : 0;
+		val = enable ? (WC0_IS_EN | WC0_IS_C(0x1)) : 0;
 		break;
 	case SSUSB_UWK_V1_2:
 		reg = mtk->uwk_reg_base + PERI_WK_CTRL0;