Quectel EG21 modem QMI connection works but MM fallbacks to ttyUSB2 as primary port

[Carl Yin(殷张成)]

Hi Aleksander:
	Maybe Rafal is same as me, newbie to the open source world, not clear the rules of open source.
	Limited by our technical ability and time, in the past , we never work together with customers to solve issues related to ModemManager
	In fact, If the product use ModemManager, the system usually is Ubuntu/Redhat/Yocto, and the kernel version usually is very new.
	We will prepare an article about "How Quectel Modems co-work with ModeManager"

On November 26, 2020 5:09 PM, Aleksander wrote:
> Hey Carl,
> 
> >         Quectel has lot of customers, and most of them are use system like
> openwrt, android, others embedded -linux.
> >         and the kernel version used is usually is V3.x,V4.x.
> >         it will spend very much time (for quectel-self and customers):
> >                          if we appiled patch to the upstream qmi_wwan
> driver, and back-port the driver to the customer's kernel.
> >         So we directly povide qmi_wwan_q.c, suitable for ALL kernel versions
> (V3.2 and later), the customers just need 'copy + paste' it.
> >
> 
> That's a fair enough reason I guess. May I suggest, though, that instead of always
> telling your customers to use the "qmi_wwan_q"
> driver, you could tell them something like "the EC21 (0x2c7c, 0x0121) is supported
> in the Linux kernel since v4.9"? Your driver should be a fallback case when the
> user is using an old kernel that doesn't support the module by default, your
> driver should not be the default IMO. Keeping a list with your module versions
> and the kernel versions where support was introduced would be a great source
> of information for your customers ;)
> 
> --
> Aleksander
> https://aleksander.es