linux-kernel - [PATCH 7/9] usb:fsl:otg: Add host-gadget drv sync delay

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Date:	Tue, 7 Apr 2015 17:28:37 +0530
From:	Ramneek Mehresh <ramneek.mehresh@...escale.com>
To:	<linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>
CC:	<balbi@...com>, <stern@...land.harvard.edu>,
	<gregkh@...uxfoundation.org>,
	Ramneek Mehresh <ramneek.mehresh@...escale.com>
Subject: [PATCH 7/9] usb:fsl:otg: Add host-gadget drv sync delay

Resolve synchronization issue between host and gadget drivers
upon role-reversal

Signed-off-by: Ramneek Mehresh <ramneek.mehresh@...escale.com>
Reviewed-by: Li Yang-R58472 <LeoLi@...escale.com>
Reviewed-by: Fleming Andrew-AFLEMING <AFLEMING@...escale.com>
Tested-by: Fleming Andrew-AFLEMING <AFLEMING@...escale.com>
---
 drivers/usb/phy/phy-fsl-usb.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/phy/phy-fsl-usb.c b/drivers/usb/phy/phy-fsl-usb.c
index ce40d5c..a3a578d 100644
--- a/drivers/usb/phy/phy-fsl-usb.c
+++ b/drivers/usb/phy/phy-fsl-usb.c
@@ -544,8 +544,17 @@ int fsl_otg_start_gadget(struct otg_fsm *fsm, int on)
 	dev = otg->gadget->dev.parent;
 
 	if (on) {
-		if (dev->driver->resume)
+		/* Delay gadget resume to synchronize between host and gadget
+		 * drivers. Upon role-reversal host drv is shutdown by kernel
+		 * worker thread. By the time host drv shuts down, controller
+		 * gets programmed for gadget role. Shutting host drv after
+		 * this results in controller getting reset, and it stops
+		 * responding to otg events
+		 */
+		if (dev->driver->resume) {
+			msleep(1000);
 			dev->driver->resume(dev);
+		}
 	} else {
 		if (dev->driver->suspend)
 			dev->driver->suspend(dev, otg_suspend_state);
-- 
1.8.3.1

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