From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============9180554784997400109==" MIME-Version: 1.0 From: Denis Kenzior Subject: Re: Quectel EC200T USB: Problems with context activation Date: Wed, 06 Jan 2021 13:52:27 -0600 Message-ID: In-Reply-To: List-Id: To: ofono@ofono.org --===============9180554784997400109== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Hi Sergei, > So far, all modems on this planet have honored the default properly... > = > Sorry for my misunderstanding. I should have read the RFC better but this= aspect = > is defined > properly only in the following clause - > "TheConfiguration Option is used to inform the peer which control > = > characters MUST remain mapped when the peer sends them." > = > So I have managed to find this after your message. Thank you. > = > So you have two options for fixing this: > =C2=A0 =C2=A0- Make GAtPPP negotiate a default ACCM in all cases > = > =C2=A0 =C2=A0- Override the negotiated ACCM (using g_at_hdlc_set_rec= v_accm for your > particular modem. > = > I think that this modem is buggy as you have clearly shown. I agree that = it is = > not a good idea to > do something which does not follow the RFCs fine. But, I feel that the de= fault = I don't remember why we chose not to negotiate the RX ACCM. Things may hav= e = worked wonderfully with the defaults, so maybe we just decided not to touch= it. > value for ACCM > is not that one we should use. Excuse me if I am too direct here, I am no= t an = > expert in this field > but I think it is better for DTE to send a configuration request with ACC= M =3D = > 0x00000000 > as pppd does because this allows us to send more information in the same = number = > of bytes. > Would you agree? If not I will override the negotiated ACCM, if it is lef= t = I think that makes sense. > default, for this > chinese modem because I do not feel that they could update the firmware t= o = > fulfill the RFC > requirements=C2=A0in a reasonable=C2=A0amount of time if they even would.= =C2=A0I do not think = > that they > would even find this necessary if I had told them. Well, it isn't a 'requirement' to use the defaults. What happened in this = particular case is that we didn't explicitly tell the modem side what RX AC= CM we = want, and the modem firmware didn't use the defined default values. I think it should be safe for us to use an ACCM of 0 instead of the RFC def= ault. = But just in case, we should probably provide a way for the driver to over= ride = it if needed. So what I would do is: - Set REQ_OPTION_ACCM in the lcp init somewhere. Set the initial value to = be 0 = as you suggest. - Add g_at_ppp_set_accm() in order to allow drivers to provide a custom ACC= M to = negotiate, if needed. Regards, -Denis --===============9180554784997400109==--