linux-kernel - Re: [RESEND PATCH v3 1/2] usb: dwc3: gadget: Add disconnect checking when changing function dynamically

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Date:   Thu, 13 Oct 2016 10:28:44 +0200
From:   Janusz Dziedzic <janusz.dziedzic@...to.com>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Mark Brown <broonie@...nel.org>,
        USB <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v3 1/2] usb: dwc3: gadget: Add disconnect checking
 when changing function dynamically

On 13 October 2016 at 10:21, Baolin Wang <baolin.wang@...aro.org> wrote:
> Hi,
>
> On 13 October 2016 at 16:16, Janusz Dziedzic <janusz.dziedzic@...to.com> wrote:
>> On 13 October 2016 at 09:37, Baolin Wang <baolin.wang@...aro.org> wrote:
>>> Hi,
>>>
>>> On 13 October 2016 at 15:06, Felipe Balbi <balbi@...nel.org> wrote:
>>>>
>>>> Hi,
>>>>
>>>> Baolin Wang <baolin.wang@...aro.org> writes:
>>>>> When system has stpped the gadget, we should avoid queuing any requests
>>>>
>>>> queueing is *not* a problem. Starting is. In fact, that's what your
>>>> patch is doing.
>>>
>>> OK.
>>>
>>>>
>>>>> which will cause tranfer failed. Thus adding some disconnect checking to
>>>>                    ^^^^^^^
>>>>                    transfer
>>>
>>> Sorry for spelling mistake, will fix it.
>>>
>>>>
>>>>> avoid this situation.
>>>>>
>>>>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>>>>> ---
>>>>> Changes since v2:
>>>>>  - Move disconnect checking into dwc3_send_gadget_ep_cmd().
>>>>>  - Rename completion name and issue complete() at one place.
>>>>>  - Move completion initialization into dwc3_gadget_init().
>>>>>
>>>>> Changes since v1:
>>>>>  - Split into 2 separate ptaches.
>>>>>  - Choose complete mechanism instead of polling.
>>>>> ---
>>>>>  drivers/usb/dwc3/gadget.c |    3 +++
>>>>>  1 file changed, 3 insertions(+)
>>>>>
>>>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>>>> index 1783406..ca2ae5b 100644
>>>>> --- a/drivers/usb/dwc3/gadget.c
>>>>> +++ b/drivers/usb/dwc3/gadget.c
>>>>> @@ -241,6 +241,9 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned cmd,
>>>>>       int                     susphy = false;
>>>>>       int                     ret = -EINVAL;
>>>>>
>>>>> +     if (!dwc->pullups_connected)
>>>>> +             return -ESHUTDOWN;
>>>>> +
>>
>> you skip trace_dwc3_gadget_ep_cmd()
>
> Yes, we did not need trace here since we did not send out the command.
>
What in such case: enumeration will not work and this will be because
this ESHUTDOWN or wrong pullups_connected usage. Without a trace you
will not know where the problem is.
In my opinion this trace could be useful.

BR
Janusz

>>
>> BR
>> Janusz
>>
>>>>>       /*
>>>>>        * Synopsys Databook 2.60a states, on section 6.3.2.5.[1-8], that if
>>>>>        * we're issuing an endpoint command, we must check if
>>>>> --
>>>>> 1.7.9.5
>>>>>
>>>>> --
>>>>> To unsubscribe from this list: send the line "unsubscribe linux-usb" in
>>>>> the body of a message to majordomo@...r.kernel.org
>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>
>>>> --
>>>> balbi
>>>
>>>
>>>
>>> --
>>> Baolin.wang
>>> Best Regards
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-usb" in
>>> the body of a message to majordomo@...r.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
>
> --
> Baolin.wang
> Best Regards