[v5] cdc-acm: fix abnormal DATA RX issue for Mediatek Preloader.

[macpaul.lin@mediatek.com]

On Wed, 2018-12-19 at 01:48 +0800, Macpaul Lin wrote:
> On Tue, 2018-12-18 at 23:42 +0700, Lars Melin wrote:
> > On 12/18/2018 22:19, Macpaul Lin wrote:
> > 
> > 
> > > Hi all,
> > > 
> > > After double check the PID/VID officially used (registered) by Mediatek
> > > Inc. The following VID/PID maps to the corresponding USB interface of
> > > the firmware of cell phone.
> > > VID:0x0e8d, PID:0x0003: Mediatek BROM.
> > > VID:0x0e8d, PID:0x2000: Mediatek Preloader.
> > > 
> > > I will update Patch v6 for changing Andrey's previous comments.
> > > 
> > 
> > You should show us a verbose lsusb of your 0e8d:0003 before changing
> > Andrey's submission.
> > 
> > 
> > Season's Greeting
> > Lars
> 
> 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
> pasted in this tutorial, too.
> Sorry for the proprietary information policy I cannot paste them all,
> but the VID/PID set of BROM and Preloader are just exactly the same
> as described in this tutorial.
> 

Hi all,
Here is the lsusb dump of the BROM and Preloader state of the phone.

lsusb of BROM:
Bus 001 Device 012: ID 0e8d:0003 MediaTek Inc. MT6227 phone

lsusb of Preloader:
Bus 001 Device 011: ID 0e8d:2000 MediaTek Inc. MT65xx Preloader

dmesg of BROM:
[52138.849233] usb 1-1: new high-speed USB device number 12 using
ehci-pci
[52139.252557] usb 1-1: New USB device found, idVendor=0e8d,
idProduct=0003
[52139.252559] usb 1-1: New USB device strings: Mfr=0, Product=0,
SerialNumber=0
[52139.260179] cdc_acm 1-1:1.0: ttyACM0: USB ACM device

dmesg of Preloader:
[52145.052952] usb 1-1: new high-speed USB device number 13 using
ehci-pci
[52145.410432] usb 1-1: New USB device found, idVendor=0e8d,
idProduct=2000
[52145.410434] usb 1-1: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
[52145.410435] usb 1-1: Product: MT65xx Preloader
[52145.410437] usb 1-1: Manufacturer: MediaTek

Regards,
Macpaul Lin