linux-kernel - Re: [PATCH] dwc3: gadget: Defer starting the gadget device until gadget is power on

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Message-ID: <CAMz4kuJZgBtg_Si9=rExEESnPjRv5o9O842-4M+sZ8i8f4zAzw@mail.gmail.com>
Date:	Wed, 18 May 2016 19:26:56 +0800
From:	Baolin Wang <baolin.wang@...aro.org>
To:	Felipe Balbi <balbi@...nel.org>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	Mark Brown <broonie@...nel.org>,
	USB <linux-usb@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dwc3: gadget: Defer starting the gadget device until
 gadget is power on

On 18 May 2016 at 19:21, Felipe Balbi <balbi@...nel.org> wrote:
>
> Hi,
>
> Baolin Wang <baolin.wang@...aro.org> writes:
>>>>>> @@ -1748,15 +1754,25 @@ static int dwc3_gadget_start(struct usb_gadget *g,
>>>>>>          * even though host mode might be active. Don't actually perform
>>>>>>          * device-specific initialization until device mode is activated.
>>>>>>          */
>>>>>>
>>>>>> +       if (pm_runtime_suspended(dwc->dev)) {
>>>>>> +               spin_unlock_irqrestore(&dwc->lock, flags);
>>>>>> +               return 0;
>>>>>> +       }
>>>>>>
>>>>>> +       ret = __dwc3_gadget_start(dwc);
>>>>>> +       if (ret)
>>>>>> +               goto err1;
>>>>>>
>>>>>> So I think the dwc3 core can enter suspend mode before gadget function
>>>>>> is ready to call the 'usb_gadget_udc_start()' and
>>>>>> 'usb_udc_connect_control()', then if the dwc3 core has entered
>>>>>> suspended mode, we need to return success when starting the gadget,
>>>>>> and leave the gadget starting action from gadget resume. What do you
>>>>>> think about that? Thanks.
>>>>>
>>>>> Well, if this makes it work properly. Then, yeah; looks okay to me. I'll
>>>>> add this to the patch introducing runtime PM.
>>>>
>>>> OK.
>>>
>>> I've updated the branch with slightly modified version of your
>>> changes. Can you test again just to make sure it still works ?
>>>
>>> Basically, here's what I did:
>>>
>>> on dwc3_gadget_start:
>>>
>>> -       __dwc3_gadget_start(dwc);
>>> +       if (pm_runtime_active(dwc->dev))
>>> +               __dwc3_gadget_start(dwc);
>>> +
>>
>> Great.
>>
>>>
>>> on run_stop, I kept the same thing.
>>>
>>> you just need to replace "usb: dwc3: implement runtime PM" with the new
>>> version from my branch.
>>
>> Yeah, it can work well on my platform with your new patch.
>
> cool, thanks again :-) I'll drop my "not for merging note" and add your
> "Tested-by" (assuming it's okay for you that I do it).

It's okay for me. Thanks.

>
> cheers
>
> --
> balbi



-- 
Baolin.wang
Best Regards