linux-kernel - [RFC][PATCH] usb: dwc2: Make sure we disconnect the gadget state on reset

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Date:   Wed, 19 Oct 2016 23:00:41 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     John Stultz <john.stultz@...aro.org>,
        Wei Xu <xuwei5@...ilicon.com>,
        Guodong Xu <guodong.xu@...aro.org>,
        Chen Yu <chenyu56@...wei.com>,
        Amit Pundir <amit.pundir@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        John Youn <johnyoun@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org
Subject: [RFC][PATCH] usb: dwc2: Make sure we disconnect the gadget state on reset

I had seen some odd behavior with HiKey's usb-gadget interface
that I finally seemed to have chased down. Basically every other
time I pluged in the OTG port, the gadget interface would
properly initialize. The other times, I'd get a big WARN_ON
in dwc2_hsotg_init_fifo() about the fifo_map not being clear.

Ends up If we don't disconnect the gadget state on reset, the
fifo-map doesn't get cleared properly, which causes WARN_ON
messages and also results in the device not properly being
setup as a gadget every other time the OTG port is connected.

So this patch adds a call to dwc2_hsotg_disconnect() in the
reset path so the state is properly cleared.

With it, the gadget interface initializes properly on every
plug in.

I don't know if this is actually the right fix, but it seems
to work well. Feedback would be greatly appreciated!

Cc: Wei Xu <xuwei5@...ilicon.com>
Cc: Guodong Xu <guodong.xu@...aro.org>
Cc: Chen Yu <chenyu56@...wei.com>
Cc: Amit Pundir <amit.pundir@...aro.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
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: John Stultz <john.stultz@...aro.org>
---
 drivers/usb/dwc2/gadget.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 24fbebc..5505001 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -2519,6 +2519,8 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,

 	/* Kill any ep0 requests as controller will be reinitialized */
 	kill_all_requests(hsotg, hsotg->eps_out[0], -ECONNRESET);
+	/* Make sure everything is disconnected */
+	dwc2_hsotg_disconnect(hsotg);

 	if (!is_usb_reset)
 		if (dwc2_core_reset(hsotg))
-- 
2.7.4