Hi Tonny,

> But it seems to me the gprs context will be pass to modem plugins, so we
> need to set the vendor code for Huawei modems, because it sends unquoted
> strings.

No, you don't.  You are confusing gprs atom and the gprs-context atom.
Grep for VENDOR in drivers/atmodem/gprs-context.c if you do not believe
me.  There is no vendor specific code in the atmodem gprs-context driver.

> 
> For example, please correct me if wrong, when the network registration
> status changed, ofono will invoke modem's set_attached() to handle the
> modem attach/detach.  Then, in gprs_attach_callback() in src/gprs.c, it
> will invokes modem's attached_status() to check the modem state, which
> has vendor dependent code in it.  Most importantly, after ofono sending
> AT+CGREG? to query the solicited response, the at_cgreg_cb() requires
> the correct vendor  ID so that at_util_parse_reg() knows whether the lac
> and ci are quoted strings or not?  Did I misunderstand?  Thanks.

As I mentioned before, this is needed for the gprs atom driver which
handles the CGREG parsing.  Not for gprs-context driver.

Regards,
-Denis