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

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Date:	Wed, 18 May 2016 13:22:45 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	Baolin Wang <baolin.wang@...aro.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


Hi,

Baolin Wang <baolin.wang@...aro.org> writes:
>>> @@ -1485,16 +1490,11 @@ static int dwc3_gadget_run_stop(struct dwc3
>>> *dwc, int is_on, int suspend)
>>>  {
>>>         u32                     reg;
>>>         u32                     timeout = 500, i;
>>>
>>> +       if (pm_runtime_suspended(dwc->dev))
>>> +               return 0;
>>>
>>> (2)
>>> @@ -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);
+

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.

cheers

-- 
balbi

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