[10/15] usb: dwc3: gadget: Set maxpacket size for ep0 IN

[Felipe Balbi <balbi@kernel.org>]

Hi,

Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
> Hi,
>
> On 1/8/2018 4:06 AM, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>> There are 2 control endpoint structures for DWC3. However, the driver
>>> only updates the OUT direction control endpoint structure during
>>> ConnectDone event. DWC3 driver needs to update the endpoint max packet
>>> size for control IN endpoint as well. If the max packet size is not
>>> properly set, then the driver will incorrectly calculate the data
>>> transfer size and fail to send ZLP for HS/FS 3-stage control read
>>> transfer.
>>>
>>> The fix is simply to update the max packet size for the ep0 IN direction
>>> during ConnectDone event.
>>>
>>> Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
>>> ---
>>>   drivers/usb/dwc3/gadget.c | 2 ++
>>>   1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index bdf2a2014ebd..6ae924d95cbc 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -2751,6 +2751,8 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
>>>   		break;
>>>   	}
>>>   
>>> +	dwc->eps[1]->endpoint.maxpacket = dwc->gadget.ep0->maxpacket;
>> 
>> thanks :-) I've had that on my list for a while but never got to it
>> since it has no real effects other than reporting properly on
>> tracepoints :-)
>> 
>
> Just to clarify, this is a bug. We found this issue when we test for 
> HS/FS 3-stage control read transfer for ZLP.

interesting... I have never seen such bug before. Got some tracepoints
of the problem? Also, if it's a bug, why wasn't it sent as a separate
patch with a Cc stable and a Fixes tag?