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From:   Anurag Kumar Vulisha <anuragku@xilinx.com>
To:     Felipe Balbi <balbi@kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
CC:     "v.anuragkumar@gmail.com" <v.anuragkumar@gmail.com>,
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        "Thinh.Nguyen@synopsys.com" <Thinh.Nguyen@synopsys.com>,
        Ajay Yugalkishore Pandey <APANDEY@xilinx.com>
Subject: RE: [PATCH v5 0/8] usb: dwc3: Fix broken BULK stream support to dwc3
 gadget driver
Thread-Topic: [PATCH v5 0/8] usb: dwc3: Fix broken BULK stream support to dwc3
 gadget driver
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Date:   Tue, 9 Oct 2018 06:38:21 +0000
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Hi Felipe,

>-----Original Message-----
>From: Felipe Balbi [mailto:balbi@kernel.org]
>Sent: Tuesday, October 09, 2018 11:07 AM
>To: Anurag Kumar Vulisha <anuragku@xilinx.com>; Anurag Kumar Vulisha
><anuragku@xilinx.com>; gregkh@linuxfoundation.org
>Cc: v.anuragkumar@gmail.com; linux-usb@vger.kernel.org; linux-
>kernel@vger.kernel.org; Thinh.Nguyen@synopsys.com; Ajay Yugalkishore Pande=
y
><APANDEY@xilinx.com>
>Subject: RE: [PATCH v5 0/8] usb: dwc3: Fix broken BULK stream support to d=
wc3
>gadget driver
>
>
>(no top-posting, please)
>

Will ensure this won't happen again

>Hi,
>
>
>Anurag Kumar Vulisha <anuragku@xilinx.com> writes:
>
>> Hi Felipe,
>>
>> Please let us know if you have any suggestions / comments on this patch =
series.
>> If you feel this patch series are okay, can we proceed with them?
>
>I really don't like this dwc3-specific timer. The best way here would be
>to add a timer on udc/core.c which can be reused by any udc. This would
>mean, of course, teaching udc/core about streams and lettting it do part
>of the handling.
>

Thanks for spending your time in reviewing this patch. The reason for addin=
g the
timer is when streams are enabled there could be chances for the host and g=
adget
controller to become out of sync, the gadget may wait for the host to issue=
 prime
transaction and the host may wait for the gadget to issue ERDY. To avoid su=
ch a
potential deadlock conditions, timeout needs to be implemented in dwc3 driv=
er.
After timeout occurs, gadget will first stop transfer and restart the trans=
fer again.
This issue is mentioned in databook 2.90A section 9.5.2. I am not aware of =
how
other controllers are handling the streams, but since this issue looks more=
 like a
dwc3 specific issue, I think it would be more convincing to add the timer i=
n dwc3
gadget driver rather than adding in udc framework. Also we are stopping the=
 timer
when a valid StreamEvnt is found, which would be difficult to handle if the=
 timer is
moved into udc. Please help me by correcting , if I am missing something or=
 my
understanding is wrong.

Thanks,
Anurag Kumar Vulisha

>Best
>
>--
>balbi