From: Lars Poeschel <poeschel@lemonage.de>
To: Alan Cox <alan@linux.intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
jslaby@suse.cz, linux-kernel@vger.kernel.org,
xiaojin <jin.xiao@intel.com>, Ken Mills <ken.k.mills@intel.com>,
Dirkjan Bussink <d.bussink@gmail.com>
Subject: Re: [RFC DO NOT MERGE] tty: n_gsm: support buggy modem
Date: Wed, 08 Jan 2014 14:26:03 +0100 [thread overview]
Message-ID: <1599574.bGW69LnCZ1@lem-wkst-02> (raw)
In-Reply-To: <1389113497.2735.142.camel@acox1-desk.ger.corp.intel.com>
Am Dienstag, 7. Januar 2014, 16:51:37 schrieb Alan Cox:
> > > modem status command, but this DV bit is not set. With this patch the
> > > modem
> > > and the whole mux is working fine. Another way makeing all this work is
> > > setting the carrier_raised function to NULL. The tty code assumes that
> > > everything is alright then.
>
> Which means your modem has decided it doesn't yet have a carrier. Do you
> get a carrier after ATD completes with a CONNECTED message ?
>
> (you can open with O_NDELAY to avoid blocking on the open)
Oh! Thank you! This does indeed bring up the channel. After opening
nonblocking and writing ATD *99***1# to a muxed channel the modem sends a
modem status command message with DV bit set.
This does in fact mean, I can only use the mux in nonblocking mode. Does this
make sense ? Why can't I use a muxed channel with blocking IO ? I could do AT
commands over the mux channel and the DV bit is not set (and thus TIOCM_CD is
not set) and the modem (and the mux line discipline) is fine with it.
next prev parent reply other threads:[~2014-01-08 13:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-07 13:05 Lars Poeschel
2014-01-07 14:20 ` Greg KH
2014-01-07 16:51 ` Alan Cox
2014-01-08 13:26 ` Lars Poeschel [this message]
2014-01-07 16:58 ` Lars Poeschel
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