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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Fabien Parent <fparent@baylibre.com>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Macpaul Lin <macpaul.lin@mediatek.com>,
        Tainping Fang <tianping.fang@mediatek.com>
Subject: [PATCH 5.4 05/84] usb: mtu3: fix USB 3.0 dual-role-switch from device to host
Date:   Wed,  4 May 2022 18:43:46 +0200
Message-Id: <20220504152928.124644155@linuxfoundation.org>
In-Reply-To: <20220504152927.744120418@linuxfoundation.org>
References: <20220504152927.744120418@linuxfoundation.org>
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From: Macpaul Lin <macpaul.lin@mediatek.com>

commit 456244aeecd54249096362a173dfe06b82a5cafa upstream.

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")
Cc: stable@vger.kernel.org
Tested-by: Fabien Parent <fparent@baylibre.com>
Reviewed-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Signed-off-by: Tainping Fang <tianping.fang@mediatek.com>
Link: https://lore.kernel.org/r/20220419081245.21015-1-macpaul.lin@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/mtu3/mtu3_dr.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/drivers/usb/mtu3/mtu3_dr.c
+++ b/drivers/usb/mtu3/mtu3_dr.c
@@ -41,10 +41,8 @@ static char *mailbox_state_string(enum m
 
 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 */