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

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Date:   Tue, 25 Oct 2016 14:29:31 -0700
From:   John Youn <John.Youn@...opsys.com>
To:     John Stultz <john.stultz@...aro.org>,
        lkml <linux-kernel@...r.kernel.org>
CC:     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 <John.Youn@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [RFC][PATCH] usb: dwc2: Make sure we disconnect the gadget state
 on reset

On 10/19/2016 11:00 PM, John Stultz wrote:
> 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))
> 

Seems fine with our testing.

Acked-by: John Youn <johnyoun@...opsys.com>

Regards,
John