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

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Message-Id: <20191016033340.1288-3-john.stultz@linaro.org>
Date:   Wed, 16 Oct 2019 03:33:31 +0000
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     Yu Chen <chenyu56@...wei.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        ShuFan Lee <shufan_lee@...htek.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Felipe Balbi <balbi@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Jun Li <lijun.kernel@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Jack Pham <jackp@...eaurora.org>, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, John Stultz <john.stultz@...aro.org>
Subject: [RFC][PATCH v3 02/11] usb: dwc3: Execute GCTL Core Soft Reset while switch modes

From: Yu Chen <chenyu56@...wei.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@...uxfoundation.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
CC: ShuFan Lee <shufan_lee@...htek.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>
Cc: Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc: Yu Chen <chenyu56@...wei.com>
Cc: Felipe Balbi <balbi@...nel.org>
Cc: Hans de Goede <hdegoede@...hat.com>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Jun Li <lijun.kernel@...il.com>
Cc: Valentin Schneider <valentin.schneider@....com>
Cc: Jack Pham <jackp@...eaurora.org>
Cc: linux-usb@...r.kernel.org
Cc: devicetree@...r.kernel.org
Signed-off-by: Yu Chen <chenyu56@...wei.com>
Signed-off-by: John Stultz <john.stultz@...aro.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