[PATCH] ublox: use ID_MM_UBLOX_PORT_READY_DELAY udev flag as init

[Matthew Starr]

> -----Original Message-----
> From: Aleksander Morgado [mailto:aleksander at aleksander.es]
> Sent: Monday, May 07, 2018 10:59 AM 
> On Mon, May 7, 2018 at 4:32 PM, Matthew Starr <mstarr at hedonline.com>
> wrote:
> >> -----Original Message-----
> >> From: Aleksander Morgado [mailto:aleksander at aleksander.es]
> >> Sent: Saturday, May 05, 2018 7:31 AM
> >>
> >> >> > > How about having a single call reading the udev tag value in
> >> >> > > ublox_custom_init() and passing the value to wait_for_ready()?
> >> >> > >
> >> >> > > E.g.
> >> >> > > static void
> >> >> > > wait_for_ready (GTask *task,
> >> >> > >                 guint wait_timeout_secs)
> >> >> > > {
> >> >> > > ...
> >> >> > > }
> >> >> > >
> >> >> >
> >> >> > The only issue with that is wait_for_ready() is also called by the
> >> >> quick_at_ready() function which is a callback function, so I can't pass in
> >> the
> >> >> wait_timeout_secs to that instance.  I was thinking instead of adding
> >> >> wait_timeout_secs to the CustomInitContext struct since that is
> already
> >> >> available to the wait_for_ready() function no matter how it is called.
> Then
> >> >> ctx->wait_timeout_secs can be set in the ublox_custom_init()
> function,
> >> >> unless you have another recommendation.
> >> >>
> >> >> Oh, that's totally fine. Just read it once and store it in the
> >> >> CustomInitContext.
> >> >>
> >> >
> >> > One additional item is I found to reliably get the TOBY-R200 to initialize
> with
> >> ModemManager I needed to have it use a 2 second delay using the
> >> ID_MM_UBLOX_PORT_READY_DELAY udev flag in the 77-mm-ublox-port-
> >> types.rules file.  Without this the modem is sometimes never initialized by
> >> MM.  I am planning on adding that to the new patch I will be sending too.
> >> >
> >>
> >> Humm.... but does the TOBY-R200 send the +READY URC before those 2s?
> >> I don't understand why that would be needed really. Could you send
> >> some logs with/without the 2s timeout to see the differences?
> >>
> >
> > The TOBY-R200 does not send a +READY URC message.  The root issue is
> that when the USB serial devices (ttyACM) appear they are not really ready
> for communication yet.  This delay interface just happened to be an easy way
> to apply a delay at startup, but I can see how this is outside the code's
> intended use.
> >
> > Apparently several of the modems that u-blox has can send greeting text
> which by default is turned off, and when turned on the default greeting is a
> blank string.  Since the defaults have to be assumed, the use of the greeting
> on other u-blox modems will not be useful to determine when the modem is
> ready to communicate.
> >
> > If you want I can take out the 2 second delay from the patch and resubmit
> without that.
> >
> 
> I believe the patch should go without 2 second delay, yes.

I will resubmit the patch without it.

> 
> > I attached the logs with and without the delay for you to review.  You can
> see in the one without the delay MM never is able to get the modem to
> respond to the AT command even after 10 minutes of trying.
> >
> 
> I'm extremely confused by this log (the one "without delay"). Is this
> log obtained running from git master without any other patch on top?
> Did you manually modify anything in the code to get this log? I would
> expect to see "AT" commands *sent* to the device via the ttyACMx
> interfaces and I'm not seeing those in the logs.
> 

This is the master branch of MM with my patch (but without the 2 second delay on the TOBY-R200).  I thought this was weird too.

It looks like the +READY URC delay of 20 seconds that my patch replaces was avoiding/masking this issue with the TOBY-R200 modem.

I connected to the modem directly using picocom when this issue occurs with MM and the modem responds to "AT" with "OK".  Also other AT commands I tried worked fine.  I tried this on all 3 USB serial lines that have AT interfaces.

Adding in a small delay before probing the modem seems to resolve the issue, or at least is a work around since I am not sure what is causing the issue.

Regards,
Matthew Starr