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Subject: Re: [PATCH v5] cdc-acm: fix abnormal DATA RX issue for Mediatek
 Preloader.
To: Macpaul Lin <macpaul.lin@mediatek.com>
Cc: Oliver Neukum <oneukum@suse.com>,
        Andrey Arapov <andrey.arapov@gmail.com>,
        Johan Hovold <johan@kernel.org>,
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From: Lars Melin <larsm17@gmail.com>
Message-ID: <f1c4469b-7ddf-d43e-0793-e9786a7a5c31@gmail.com>
Date: Wed, 19 Dec 2018 07:45:20 +0700
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On 12/19/2018 00:48, Macpaul Lin wrote:

> Hi Lars, Oliver, and Johan,
> 
> Well, it's about 1:30 a.m. here in Taiwan. I can do lsusb dump tomorrow
> in Mediatek's office.
> But there are a lot of tutorials about hacking and flash method of
> customized firmware over the WWW. I can find one of the tutorial shows
> these VID/PID combinations has been used since 2014.
> (Actually they've been registered officially earlier than 2014.)
> 
> For example, please check the reference tutorial:
> https://mattboyer.github.io/PYaffs/2014/07/31/Hacklog%233.html
> You can check lsusb dump in this picture.
> https://mattboyer.github.io/PYaffs/images/03_device_usbview.png
> Both VID/PID of Mediatek BROM and Preloader can be found in INF file


Hi Macpaul,

the picture of an lsusb dump is not complete and does not show if there 
are union descriptors or if they are missing.
Since you remove Andrey's NO UNION DESCRIPTOR quirk then you have to 
show that there are union descriptors in your device.
If there are union descriptors in it then Mediatek has used the same 
vid:pid for two devices that differs from each other.

/Lars