Re: [MM] [PATCH 3/3] ZTE: improperly USSD-query encoding

[Aleksander Morgado <aleksander lanedo com>]

On 16/04/12 18:00, Alexander Orlov wrote:
> When I send an USSD query, it should be encoded to proper charset (UCS2
> in my case). But it is not. Because of this USSD queries do not work at
> all on my ZTE MF192 modem:
>
> (ttyACM0): -->  'AT+CUSD=1,"*100#",15<CR>'
> (ttyACM0):<-- '<CR><LF>ERROR<CR><LF>'
>
> In git logs I have found this commit:
> http://cgit.freedesktop.org/ModemManager/ModemManager/commit/plugins/mm-modem-zte.c?id=a57618b091faec24d22bfce5f384248c52cd2511
>
> It disables hex encoding for USSD requests for all ZTE modems.
>
> With that patch reversed, USSD works fine for me:
>
> (ttyACM0): -->  'AT+CUSD=1,"002A0031003000300023",15<CR>'
> (ttyACM0):<-- '<CR><LF>+CUSD: 0,"04110430043B0430043D0441003A003600390037002C0039003604400020041E043F043B0430044204300020043A043004400442043E04390020043F043E00200431002F043F002004420435043B04350444043E043D04430020002B00370034003900350037003600360030003100360036",72<CR><LF><CR><LF>OK<CR><LF>'
> decode_ussd_response(): USSD data coding scheme 72
>
> So, I think, ModemManager should match modem model and decide, if it
> needs hex encodings. What do you think about this?

If the case is that some models don't allow UCS2-hex encoded strings 
even if UCS2 is the desired charset; then I would default to trying to 
use the specified charset and if it fails, then try with the fallback 
MM_MODEM_GSM_USSD_SCHEME_7BIT as in that patch. It would just need one 
failure to really decide which logic to use. Otherwise we'll end up 
needing to maintain some table of devices showing that behaviour, which 
is possibly not a good thing to do.

--
Aleksander