usb: mtu3: 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 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.
Fixes: b1a344589eea ("usb: mtu3: support ip-sleep wakeup for MT8183")
Cc: stable@vger.kernel.org
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20210826083637.33237-2-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/mtu3/mtu3_plat.c b/drivers/usb/mtu3/mtu3_plat.c
index 5b3f7f7..f135310 100644
--- a/drivers/usb/mtu3/mtu3_plat.c
+++ b/drivers/usb/mtu3/mtu3_plat.c
@@ -63,6 +63,9 @@ static int wait_for_ip_sleep(struct ssusb_mtk *ssusb)
if (ret) {
dev_err(ssusb->dev, "ip sleep failed!!!\n");
ret = -EBUSY;
+ } else {
+ /* workaround: avoid wrong wakeup signal latch for some soc */
+ usleep_range(100, 200);
}
return ret;
