linux-kernel - [PATCH 5.4 030/120] usb: dwc3: Issue core soft reset before enabling run/stop

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Message-Id: <20220926100751.752939929@linuxfoundation.org>
Date:   Mon, 26 Sep 2022 12:11:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Wesley Cheng <quic_wcheng@...cinc.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 030/120] usb: dwc3: Issue core soft reset before enabling run/stop

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

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index f4655665a1b5..a9c49b2ce511 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -227,7 +227,7 @@ 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 a93c61bc5a7d..f320b989abd2 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1422,6 +1422,8 @@ 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 079919b85d87..b95fc2ae8074 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2088,6 +2088,17 @@ 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