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From: Felipe Balbi <balbi@ti.com>
To: Alan Stern <stern@rowland.harvard.edu>,
	Jassi Brar <jassisinghbrar@gmail.com>
CC: Jaswinder Singh <jaswinder.singh@linaro.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	<stable@vger.kernel.org>
Subject: Re: [PATCH] usb: gadget: function: acm: return zlp for OUT setup
In-Reply-To: <Pine.LNX.4.44L0.1510141341320.1644-100000@iolanthe.rowland.org>
References: <Pine.LNX.4.44L0.1510141341320.1644-100000@iolanthe.rowland.org>
Date: Wed, 14 Oct 2015 13:32:09 -0500
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Hi,

Alan Stern <stern@rowland.harvard.edu> writes:
> On Wed, 14 Oct 2015, Jassi Brar wrote:
>
>> BTW, should the gadget stack ever queue a Non-ZLP as reply to some
>> setup request that has USB_DIR_IN not set?
>
> Yes.  If USB_DIR_IN is not set then the control transfer is OUT, so the
> gadget needs to queue a request to receive some data from the host.=20=20
> That request will obviously need to be a non-ZLP.  In fact, it's hard
> to think of a situation where a gadget would ever want to submit a
> zero-length OUT request.  Isn't the UDC driver supposed to handle the
> status stage of a control-IN transfer automatically?

yes and no. :-) If USB_GADGET_DELAYED_STATUS is returned, we need to
wait for the gadget driver to queue a request.

=2D-=20
balbi

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