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From:   Henry Lin <henryl@nvidia.com>
To:     Peter Chen <peter.chen@nxp.com>
CC:     Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Romain Izard <romain.izard.pro@gmail.com>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] usb: gadget: f_ncm: fix wrong usb_ep
Thread-Topic: [PATCH] usb: gadget: f_ncm: fix wrong usb_ep
Thread-Index: AQHVoCLus26pLsIkukm9vcuV6VVAeqebTyAAgAG/7Wo=
Date:   Tue, 26 Nov 2019 07:26:02 +0000
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>> Gadget driver should always use config_ep_by_speed() to initialize=0A=
>> usb_ep struct according to usb device's operating speed. Otherwise,=0A=
>> usb_ep struct may be wrong if usb devcie's operating speed is changed.=
=0A=
>>=0A=
=0A=
>Would you please share the use case how to reproduce it?=0A=
We checked again and found NCM gadget driver should not have this issue.=0A=
Please ignore this patch.=0A=
=0A=
However, we still observe similar issue in ECM and RNDIS gadget driver. Tak=
e=0A=
ECM as example, if we plug ECM gadget in high-speed host port first. And,=
=0A=
the host only set interface with alternate setting !=3D 1 (alt !=3D 1 in ec=
m_set_alt())=0A=
for ECM gadget. Then, if we unplug gadget from high-speed host port to=0A=
another super-speed host port afterwards, we will see both in_ep->desc and=
=0A=
out_ep->desc in ecm->port keep values for high-speed endpoints. Although=0A=
NCM's implementation is similar to ECM in this part, NCM doesn't have same=
=0A=
issue as it only does config_ep_by_speed() under if alt is 1.=0A=