[U-Boot] [PATCH] usb: gadget: ci_udc: implement usb_ep_ops dequeue callback

[Peng Fan <b51431@freescale.com>]

Hi Marek,

On Wed, Sep 09, 2015 at 11:24:37AM +0800, Peng Fan wrote:
>On Tue, Sep 08, 2015 at 07:17:22PM -0700, Stephen Warren wrote:
>>On 09/03/2015 03:11 PM, Marek Vasut wrote:
>>> On Tuesday, September 01, 2015 at 09:45:12 PM, Stephen Warren wrote:
>>>> On 08/30/2015 12:26 AM, Peng Fan wrote:
>>>>> Hi Stephen,
>>> 
>>> Hi,
>>> 
>>> sorry for the delayed reply, I had to dig into the code myself.
>>> 
>>>>> On Fri, Aug 28, 2015 at 08:05:36AM +0800, Peng Fan wrote:
>>>>>> Hi Stephen,
>>>>>>
>>>>>> On Thu, Aug 27, 2015 at 10:06:14AM -0600, Stephen Warren wrote:
>>>>>>> On 08/27/2015 05:08 AM, Marek Vasut wrote:
>>>>>>>> On Thursday, August 27, 2015 at 01:00:50 PM, Peng Fan wrote:
>>>>>>>>> Implement endpoint dequeue callback function.
>>>>>>>>>
>>>>>>>>> Without this function, uboot will hang when executing fastboot
>>>>>>>>> comamnd. See following flow:
>>>>>>>>> "fastboot_tx_write_str->fastboot_tx_write->usb_ep_dequeue->ep->ops->d
>>>>>>>>> equeue " without implement ci_udc dequeue function, ep->ops->dequeue
>>>>>>>>> is NULL, then uboot will hang.
>>>>>>>>>
>>>>>>>>> Tested on mx6qsabresd board with fastboot enabled.
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/usb/gadget/ci_udc.c
>>>>>>>>> b/drivers/usb/gadget/ci_udc.c
>>>>>>>>>
>>>>>>>>> +static int ci_ep_dequeue(struct usb_ep *_ep, struct usb_request
>>>>>>>>> *_req)
>>>>>>>>>
>>>>>>>>> +	if (ci_req->req.status == -EINPROGRESS) {
>>>>>>>>> +		ci_req->req.status = -ECONNRESET;
>>>>>>>>> +		if (ci_req->req.complete)
>>>>>>>>> +			ci_req->req.complete(_ep, _req);
>>>>>>>>> +	}
>>>>>>>
>>>>>>> Is there no need to reprogram the HW to abort the transfer?
>>>>>>
>>>>>> I checked linux udc driver drivers/usb/gadget/udc/fsl_qe_udc.c
>>>>>> qe_ep_dequeue->done->usb_gadget_giveback_request->"req->complete(ep,
>>>>>> req)" I did not see code to reprogram the HW to abort the transfer.
>>>>>
>>>>> Do you have further comments?
>>>>> I checked other gadget drivers in drivers/usb/gadget/, I did not see
>>>>> drivers that reprogram the HW to abort the transfer. For now, I do not
>>>>> think out a scenario to reprogram the HW to abort the transfer
>>>>
>>>> Marek, what are the semantics of this function? Is it supposed to simply
>>>> update SW state to make U-Boot not care about the transaction
>>> 
>>> Yes, that's correct.
>>> 
>>>> or is it supposed to actually stop the HW performing the transaction on
>>>> the USB bus?
>>> 
>>> No, it's not supposed to kill the transaction in hardware.
>>
>>OK, the patch seems fine then.
>>
>>>> If it's the former, then the patch is likely fine. If it's the latter,
>>>> then I think the function does need actually need to do something to
>>>> make the HW stop, or we can't implement this particular function.
>>> 
>>> Do we need this for the current release or is this for -next ?
>>
>>I assume that's a question for Peng?
>
>Since this is a bug fix, I think this patch should be in current release.
>Without this patch, boards which want to enable fastboot using ci_udc driver
>will hang.

If you have plan to pick the bug fix, please pick V2.
https://patchwork.ozlabs.org/patch/511739/

Thanks,
Peng.
>
>Regards,
>Peng.
>>
>
>-- 

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