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

[macpaul.lin@mediatek.com]

On Tue, 2018-12-18 at 14:37 +0100, Oliver Neukum wrote:
> On Di, 2018-12-18 at 13:38 +0100, Johan Hovold wrote:
> > On 
> > > @@ -1655,7 +1662,10 @@ static int acm_pre_reset(struct usb_interface *intf)
> > >  	.driver_info = NO_UNION_NORMAL, /* has no union descriptor */
> > >  	},
> > >  	{ USB_DEVICE(0x0e8d, 0x0003), /* FIREFLY, MediaTek Inc; andrey.arapov@gmail.com */
> > > -	.driver_info = NO_UNION_NORMAL, /* has no union descriptor */
> > > +	.driver_info = DISABLE_ECHO, /* DISABLE ECHO in termios flag */
> > 
> > I just noticed that you remove the NO_UNION_NORMAL here, which looks
> > wrong and definitely requires a motivation.
> > 
> > Thanks,
> > Johan
> > 
> 
> Hi,
> 
> thank you and thank you Johan.
> Unfortunately I cannot take this until the issue with the removed
> quirk is clarified.
> 
> 	Regards
> 		Oliver
> 

Hi,
Thanks Johan's help on reviewing the updated patches.
According to Andrey's patch, the commit said this change is for
"Samsung X180 China cellphone" which might be also a Mediatek SoC based
phone using Mediatek VID.
https://goo.gl/a9ddNq (I've add a url for reference here).

But I'm not sure the PID is for Mediatek's BROM or customized Preloader.
(Both should be able to apply DISABLE_ECHO flag).
Maybe I can simply update PATCH v6 by removing FIREFLY if any one has
problem here.
Let's also loop Andrey for clarification.

Thanks!

Regards,
Macpaul Lin