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 14:56:47 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     John Youn <John.Youn@...opsys.com>
Cc:     lkml <linux-kernel@...r.kernel.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>,
        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 Tue, Oct 25, 2016 at 2:29 PM, John Youn <John.Youn@...opsys.com> wrote:
> 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>

Awesome! Thanks so much for the review and testing!

I'm curious, did you happen to have any thoughts or objections on the
"dwc2: Force port resume on switching to device mode" patch
(https://patchwork.kernel.org/patch/9375965/ ) as well?

thanks
-john