[PATCH 4.9 36/96] usb: dwc3: Add SoftReset PHY synchonization delay

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>

[ Upstream commit fab3833338779e1e668bd58d1f76d601657304b8 ]

>From DWC_usb31 programming guide section 1.3.2, once DWC3_DCTL_CSFTRST
bit is cleared, we must wait at least 50ms before accessing the PHY
domain (synchronization delay).

Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/dwc3/core.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -161,7 +161,7 @@ static int dwc3_core_soft_reset(struct d
 	do {
 		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 		if (!(reg & DWC3_DCTL_CSFTRST))
-			return 0;
+			goto done;
 
 		udelay(1);
 	} while (--retries);
@@ -170,6 +170,17 @@ static int dwc3_core_soft_reset(struct d
 	phy_exit(dwc->usb2_generic_phy);
 
 	return -ETIMEDOUT;
+
+done:
+	/*
+	 * For DWC_usb31 controller, once DWC3_DCTL_CSFTRST bit is cleared,
+	 * we must wait at least 50ms before accessing the PHY domain
+	 * (synchronization delay). DWC_usb31 programming guide section 1.3.2.
+	 */
+	if (dwc3_is_usb31(dwc))
+		msleep(50);
+
+	return 0;
 }
 
 /**