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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, Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Wesley Cheng <quic_wcheng@quicinc.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 006/148] usb: dwc3: Issue core soft reset before enabling run/stop
Date:   Mon, 26 Sep 2022 12:10:40 +0200
Message-Id: <20220926100756.287627954@linuxfoundation.org>
In-Reply-To: <20220926100756.074519146@linuxfoundation.org>
References: <20220926100756.074519146@linuxfoundation.org>
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From: Wesley Cheng <quic_wcheng@quicinc.com>

[ Upstream commit 0066472de157439d58454f4a55786f1045ea5681 ]

It is recommended by the Synopsis databook to issue a DCTL.CSftReset
when reconnecting from a device-initiated disconnect routine.  This
resolves issues with enumeration during fast composition switching
cases, which result in an unknown device on the host.

Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20220316011358.3057-1-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 040f2dbd2010 ("usb: dwc3: gadget: Avoid duplicate requests to enable Run/Stop")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/dwc3/core.c   |  4 +---
 drivers/usb/dwc3/core.h   |  2 ++
 drivers/usb/dwc3/gadget.c | 11 +++++++++++
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9c24cf46b9a0..b2ea4c2448d4 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -114,8 +114,6 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
 	dwc->current_dr_role = mode;
 }
 
-static int dwc3_core_soft_reset(struct dwc3 *dwc);
-
 static void __dwc3_set_mode(struct work_struct *work)
 {
 	struct dwc3 *dwc = work_to_dwc(work);
@@ -265,7 +263,7 @@ u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type)
  * dwc3_core_soft_reset - Issues core soft reset and PHY reset
  * @dwc: pointer to our context structure
  */
-static int dwc3_core_soft_reset(struct dwc3 *dwc)
+int dwc3_core_soft_reset(struct dwc3 *dwc)
 {
 	u32		reg;
 	int		retries = 1000;
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index dbae57725f52..077d03a33388 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1510,6 +1510,8 @@ bool dwc3_has_imod(struct dwc3 *dwc);
 int dwc3_event_buffers_setup(struct dwc3 *dwc);
 void dwc3_event_buffers_cleanup(struct dwc3 *dwc);
 
+int dwc3_core_soft_reset(struct dwc3 *dwc);
+
 #if IS_ENABLED(CONFIG_USB_DWC3_HOST) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
 int dwc3_host_init(struct dwc3 *dwc);
 void dwc3_host_exit(struct dwc3 *dwc);
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 5f9a0ab09f4b..761065336322 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2515,6 +2515,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 						dwc->ev_buf->length;
 		}
 	} else {
+		/*
+		 * In the Synopsys DWC_usb31 1.90a programming guide section
+		 * 4.1.9, it specifies that for a reconnect after a
+		 * device-initiated disconnect requires a core soft reset
+		 * (DCTL.CSftRst) before enabling the run/stop bit.
+		 */
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		dwc3_core_soft_reset(dwc);
+		spin_lock_irqsave(&dwc->lock, flags);
+
+		dwc3_event_buffers_setup(dwc);
 		__dwc3_gadget_start(dwc);
 	}
 
-- 
2.35.1