linux-kernel - Re: [PATCH] usb: gadget: udc-core: call udc

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Message-id: <54A102FC.4000307@samsung.com>
Date:	Mon, 29 Dec 2014 08:30:04 +0100
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	balbi@...com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: gadget: udc-core: call udc_stop() before gadget unbind

Hi Felipe,

On 12/23/2014 07:31 PM, Felipe Balbi wrote:
> On Tue, Dec 23, 2014 at 07:34:15AM +0100, Robert Baldyga wrote:
>> On 12/22/2014 05:34 PM, Felipe Balbi wrote:
>>> On Mon, Dec 15, 2014 at 11:05:22AM +0100, Robert Baldyga wrote:
>>>> On 12/15/2014 06:13 AM, Peter Chen wrote:
>>>>> On Fri, Dec 12, 2014 at 02:17:28PM +0100, Robert Baldyga wrote:
>>>>>> As usb function drivers assumes that all usb request will be completed
>>>>>> before function unbind call, we should supply such behavior. In some
>>>>>> cases ep_disable() won't kill all request effectively, because some
>>>>>> IN requests can be in running state. In such situation it's possible
>>>>>> to have unbind function called before last request completion, which
>>>>>> can cause problems.
>>>>>
>>>>> Doesn't the function's disable/unbind should call usb_ep_dequeue to make
>>>>> sure the transfer has ended?
>>>>
>>>> USB function drivers like ECM or HID surely doesn't. It looks like
>>>> there's assumption that all requests will be completed by UDC driver.
>>>
>>> that's a bug on those drivers :-)
>>
>> So we can't make assumptions that requests will be completed in
>> ep_disable()?
> 
> oh, no you can. I misread it.
> 
>>>> Function ep_disable() should complete requests in hardware driver, but
>>>> at least in DWC2 driver not all requests are completed at this stage
>>>
>>> and that's a bug on dwc2 :-)
>>
>> I have already found that out. Another UDC drivers simply kill all
>> request without waiting for currently running, so I did the same in
>> DWC2. Here is my patch:
>> http://www.spinics.net/lists/linux-usb/msg118698.html
> 
> should be in my pull request already.

It looks like you applied wrong patch. I meant patch titled "drivers:
usb: dwc2: remove 'force' parameter from kill_all_requests()" is the
latest and complete fix. The patch you have applied named "usb: dwc2:
gadget: kill requests with 'force' in s3c_hsotg_udc_stop()" do not solve
problem completely without changes in udc-core, which we concluded are
not acceptable.

Sorry for the mess. I understand that titles of both patches are
confusing similar.

Best regards,
Robert Baldyga
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