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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,
        Rohith Kollalsi <quic_rkollals@quicinc.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 493/779] usb: dwc3: core: Do not perform GCTL_CORE_SOFTRESET during bootup
Date:   Mon, 15 Aug 2022 20:02:17 +0200
Message-Id: <20220815180358.345485471@linuxfoundation.org>
In-Reply-To: <20220815180337.130757997@linuxfoundation.org>
References: <20220815180337.130757997@linuxfoundation.org>
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From: Rohith Kollalsi <quic_rkollals@quicinc.com>

[ Upstream commit 07903626d98853e605fe63e5ce149f1b7314bbea ]

According to the programming guide, it is recommended to
perform a GCTL_CORE_SOFTRESET only when switching the mode
from device to host or host to device. However, it is found
that during bootup when __dwc3_set_mode() is called for the
first time, GCTL_CORESOFTRESET is done with suspendable bit(BIT 17)
of DWC3_GUSB3PIPECTL set. This some times leads to issues
like controller going into bad state and controller registers
reading value zero. Until GCTL_CORESOFTRESET is done and
run/stop bit is set core initialization is not complete.
Setting suspendable bit of DWC3_GUSB3PIPECTL and then
performing GCTL_CORESOFTRESET is therefore not recommended.
Avoid this by only performing the reset if current_dr_role is set,
that is, when doing subsequent role switching.

Fixes: f88359e1588b ("usb: dwc3: core: Do core softreset when switch mode")
Signed-off-by: Rohith Kollalsi <quic_rkollals@quicinc.com>
Link: https://lore.kernel.org/r/20220714045625.20377-1-quic_rkollals@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/dwc3/core.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 8adb26599797..cfac5503aa66 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -158,9 +158,13 @@ static void __dwc3_set_mode(struct work_struct *work)
 		break;
 	}
 
-	/* For DRD host or device mode only */
-	if ((DWC3_IP_IS(DWC3) || DWC3_VER_IS_PRIOR(DWC31, 190A)) &&
-	    dwc->desired_dr_role != DWC3_GCTL_PRTCAP_OTG) {
+	/*
+	 * When current_dr_role is not set, there's no role switching.
+	 * Only perform GCTL.CoreSoftReset when there's DRD role switching.
+	 */
+	if (dwc->current_dr_role && ((DWC3_IP_IS(DWC3) ||
+			DWC3_VER_IS_PRIOR(DWC31, 190A)) &&
+			dwc->desired_dr_role != DWC3_GCTL_PRTCAP_OTG)) {
 		reg = dwc3_readl(dwc->regs, DWC3_GCTL);
 		reg |= DWC3_GCTL_CORESOFTRESET;
 		dwc3_writel(dwc->regs, DWC3_GCTL, reg);
-- 
2.35.1