linux-kernel - [PATCH] usb: mtu3: fix USB 3.0 dual-role-switch from device to host

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Message-ID: <20220419081245.21015-1-macpaul.lin@mediatek.com>
Date:   Tue, 19 Apr 2022 16:12:45 +0800
From:   Macpaul Lin <macpaul.lin@...iatek.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     Miles Chen <miles.chen@...iatek.com>,
        Bear Wang <bear.wang@...iatek.com>,
        Pablo Sun <pablo.sun@...iatek.com>,
        Fabien Parent <fparent@...libre.com>,
        Mediatek WSD Upstream <wsd_upstream@...iatek.com>,
        Macpaul Lin <macpaul.lin@...iatek.com>,
        Macpaul Lin <macpaul@...il.com>, <stable@...r.kernel.org>,
        Tainping Fang <tianping.fang@...iatek.com>
Subject: [PATCH] usb: mtu3: fix USB 3.0 dual-role-switch from device to host

Issue description:
  When an OTG port has been switched to device role and then switch back
  to host role again, the USB 3.0 Host (XHCI) will not be able to detect
  "plug in event of a connected USB 2.0/1.0 ((Highspeed and Fullspeed)
  devices until system reboot.

Root cause and Solution:
  There is a condition checking flag "ssusb->otg_switch.is_u3_drd" in
  toggle_opstate(). At the end of role switch procedure, toggle_opstate()
  will be called to set DC_SESSION and SOFT_CONN bit. If "is_u3_drd" was
  set and switched the role to USB host 3.0, bit DC_SESSION and SOFT_CONN
  will be skipped hence caused the port cannot detect connected USB 2.0
  (Highspeed and Fullspeed) devices. Simply remove the condition check to
  solve this issue.

Fixes: d0ed062a8b75 ("usb: mtu3: dual-role mode support")
Signed-off-by: Macpaul Lin <macpaul.lin@...iatek.com>
Signed-off-by: Tainping Fang <tianping.fang@...iatek.com>
Tested-by: Fabien Parent <fparent@...libre.com>
Cc: stable@...r.kernel.org
---
 drivers/usb/mtu3/mtu3_dr.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/mtu3/mtu3_dr.c b/drivers/usb/mtu3/mtu3_dr.c
index ec6ec621838b..b820724c56e4 100644
--- a/drivers/usb/mtu3/mtu3_dr.c
+++ b/drivers/usb/mtu3/mtu3_dr.c
@@ -21,10 +21,8 @@ static inline struct ssusb_mtk *otg_sx_to_ssusb(struct otg_switch_mtk *otg_sx)
 
 static void toggle_opstate(struct ssusb_mtk *ssusb)
 {
-	if (!ssusb->otg_switch.is_u3_drd) {
-		mtu3_setbits(ssusb->mac_base, U3D_DEVICE_CONTROL, DC_SESSION);
-		mtu3_setbits(ssusb->mac_base, U3D_POWER_MANAGEMENT, SOFT_CONN);
-	}
+	mtu3_setbits(ssusb->mac_base, U3D_DEVICE_CONTROL, DC_SESSION);
+	mtu3_setbits(ssusb->mac_base, U3D_POWER_MANAGEMENT, SOFT_CONN);
 }
 
 /* only port0 supports dual-role mode */
-- 
2.18.0