Re: Droid 4 modem support in kernel & ofono

From: Pavel Machek <pavel@ucw.cz>
To: Tony Lindgren <tony@atomide.com>
Cc: mpartap@gmx.net, merlijn@wizzup.org, sre@kernel.org,
	kernel list <linux-kernel@vger.kernel.org>,
	nekit1000@gmail.com, ofono@ofono.org, linux-omap@vger.kernel.org,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: Droid 4 modem support in kernel & ofono
Date: Thu, 7 Feb 2019 23:17:46 +0100	[thread overview]
Message-ID: <20190207221745.GA12219@amd> (raw)
In-Reply-To: <20190201205032.GF5720@atomide.com>

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Hi!

> > Ok, so I got calls and smses somehow working in kernel&ofono ... which
> > is really all I need.
> 
> Nice :)
> 
> I think the SIM card reading and writing should be doable
> using dlci10 /dev/motmdm10 for AT+CRSM calls..

Might be. Sorry, this is outside of my area of interest, because LTE
would not be on usable frequencies, anyway.

> > I pushed the tree to git@github.com:pavelmachek/ofono.git , branch
> > d4... But I had to do some "rather interesting" hacks. D4 modem
> > expects packets and current kernel drivers rely on write() boundaries
> > and flush(). .. which is a bit of problem for in ofonod, as it expects
> > to work with bytestream with no explicit packet boundaries.
> > 
> > However D4 still uses normal AT commands, so... it would be good to be
> > able to use AT parsing framework in ofono.
> > 
> > I believe easiest solution would be to automatically do the packet
> > splitting in kernel, it should be as easy as splitting on \r and
> > ^Z. (Currently packets are only generated when \r or ^Z is seen on
> > write boundary, but that does not work well for ofono).
> 
> OK yeah it's worth trying. I hit that issue too with the
> flush needed for droid4-sms-tools scripts. And the traffic
> we're seeing is minimal and AFAIK there's no network port
> for ts27010. And SMS messages are PDU encoded anyways.
> 
> Hmm should we do it for \r\n and \r? Otherwise the \n
> will be left out of the packet :)

I guess splitting on \n makes sense, yes. 

Ofono normally uses just \r. Translating it to \r\n in kernel (ttys
already do that) would be super nice, but I think this is easy enough
to handle in ofono.

Thanks,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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