[RFC][PATCH v3 02/11] usb: dwc3: Execute GCTL Core Soft Reset while switch modes

From: John Stultz <john.stultz@linaro.org>
To: lkml <linux-kernel@vger.kernel.org>
Cc: Yu Chen <chenyu56@huawei.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	ShuFan Lee <shufan_lee@richtek.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	Felipe Balbi <balbi@kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Jun Li <lijun.kernel@gmail.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Jack Pham <jackp@codeaurora.org>,
	linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
	John Stultz <john.stultz@linaro.org>
Subject: [RFC][PATCH v3 02/11] usb: dwc3: Execute GCTL Core Soft Reset while switch modes
Date: Wed, 16 Oct 2019 03:33:31 +0000	[thread overview]
Message-ID: <20191016033340.1288-3-john.stultz@linaro.org> (raw)
In-Reply-To: <20191016033340.1288-1-john.stultz@linaro.org>

From: Yu Chen <chenyu56@huawei.com>

On the HiKey960, we need to do a GCTL soft reset when
switching modes.

Jack Pham also noted that in the Synopsys databook it
mentions performing a GCTL CoreSoftReset when changing the
PrtCapDir between device & host modes.

So this patch always does a GCTL Core Soft Reset when
changing the mode.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
CC: ShuFan Lee <shufan_lee@richtek.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Yu Chen <chenyu56@huawei.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jun Li <lijun.kernel@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Jack Pham <jackp@codeaurora.org>
Cc: linux-usb@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Yu Chen <chenyu56@huawei.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
v3: Remove quirk conditional, as Jack Pham noted the
    Synopsis databook states this should be done generally.
    Also, at Jacks' suggestion, make the reset call before
    changing the prtcap direction.
---
 drivers/usb/dwc3/core.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 999ce5e84d3c..a039e35ec7ad 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -112,6 +112,19 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
 	dwc->current_dr_role = mode;
 }
 
+static void dwc3_gctl_core_soft_reset(struct dwc3 *dwc)
+{
+	u32 reg;
+
+	reg = dwc3_readl(dwc->regs, DWC3_GCTL);
+	reg |= DWC3_GCTL_CORESOFTRESET;
+	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
+
+	reg = dwc3_readl(dwc->regs, DWC3_GCTL);
+	reg &= ~DWC3_GCTL_CORESOFTRESET;
+	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
+}
+
 static void __dwc3_set_mode(struct work_struct *work)
 {
 	struct dwc3 *dwc = work_to_dwc(work);
@@ -154,6 +167,9 @@ static void __dwc3_set_mode(struct work_struct *work)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 
+	/* Execute a GCTL Core Soft Reset when switch mode */
+	dwc3_gctl_core_soft_reset(dwc);
+
 	dwc3_set_prtcap(dwc, dwc->desired_dr_role);
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
-- 
2.17.1

