linux-kernel - [RFC][PATCH 1/2 v2] usb: dwc2: Force port resume on switching to device mode

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Date:   Wed, 19 Oct 2016 21:14:40 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     Chen Yu <chenyu56@...wei.com>, Wei Xu <xuwei5@...ilicon.com>,
        Guodong Xu <guodong.xu@...aro.org>,
        Amit Pundir <amit.pundir@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        John Youn <johnyoun@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, John Stultz <john.stultz@...aro.org>
Subject: [RFC][PATCH 1/2 v2] usb: dwc2: Force port resume on switching to device mode

From: Chen Yu <chenyu56@...wei.com>

We've seen failures when switching between host and gadget mode,
which was diagnosed as being caused due to the bus being
auto-suspended when we switched.

So this patch forces a port resume when switching to device
mode if the bus is suspended.

Cc: Wei Xu <xuwei5@...ilicon.com>
Cc: Guodong Xu <guodong.xu@...aro.org>
Cc: Amit Pundir <amit.pundir@...aro.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: John Youn <johnyoun@...opsys.com>
Cc: Douglas Anderson <dianders@...omium.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-usb@...r.kernel.org
Signed-off-by: Chen Yu <chenyu56@...wei.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/usb/dwc2/hcd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index df5a065..b374e60 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -54,6 +54,9 @@
 #include "core.h"
 #include "hcd.h"
 
+
+static void dwc2_port_resume(struct dwc2_hsotg *hsotg);
+
 /*
  * =========================================================================
  *  Host Core Layer Functions
@@ -3204,6 +3207,11 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
 	if (gotgctl & GOTGCTL_CONID_B) {
 		/* Wait for switch to device mode */
 		dev_dbg(hsotg->dev, "connId B\n");
+		if (hsotg->bus_suspended) {
+			dev_info(hsotg->dev,
+				"Do port resume before switching to device mode\n");
+			dwc2_port_resume(hsotg);
+		}
 		while (!dwc2_is_device_mode(hsotg)) {
 			dev_info(hsotg->dev,
 				 "Waiting for Peripheral Mode, Mode=%s\n",
-- 
2.7.4