Re: WIP Droid 4 voice calls, GNSS & PM with a TS 27.010 serdev driver

From: Pavel Machek <pavel@ucw.cz>
To: Tony Lindgren <tony@atomide.com>
Cc: Rob Herring <robh@kernel.org>, Marcel Partap <mpartap@gmx.net>,
	Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
	omerlle@gmail.com, Merlijn Wajer <merlijn@wizzup.org>,
	linux-kernel@vger.kernel.org, Johan Hovold <johan@kernel.org>,
	Peter Ujfalusi <peter.ujfalusi@ti.com>,
	NeKit <nekit1000@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	Michael Scott <hashcode0f@gmail.com>,
	Sebastian Reichel <sre@kernel.org>,
	linux-omap@vger.kernel.org,
	Jarkko Nikula <jarkko.nikula@bitmer.com>
Subject: Re: WIP Droid 4 voice calls, GNSS & PM with a TS 27.010 serdev driver
Date: Tue, 18 Dec 2018 21:22:42 +0100	[thread overview]
Message-ID: <20181218202242.GA30831@amd> (raw)
In-Reply-To: <20181218153650.GA6707@atomide.com>

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Hi!

> > # commit	    0c1bc81ba976bcd480d6e3c3009a28589f8427c0 (patch)
> > # mfd: motmdm: Add Motorola TS 27.010 serdev driver for devices like droid4
> > 
> > Oh, that is a lot of fun. Especially state machine for parsing modem
> > responses. I wonder how well it is going to work when modem is
> > accessed over USB... 
> > 
> > motmdm_read_state(... size_t len)
> 
> That's a bit of a layering violation yeah :) But we still need to
> do that somewhere for notifiers. And the notifications are separate
> from the commands and start with a ~ character so from that point of
> view it should not be too bad.

Plus, you seem to assume that data will always come in suitably sized
chunks. Aha, and as it is not plain serial but packet protocol over
serial... I guess that is going to work?

> > I did a quick test in my config... and it did not break my old setup
> > -- voice calls still work when set up over USB and with manual mixer
> > setup. That was good surprise.
> 
> OK good to hear. Using the n_gsm port instead of USB during idle
> has a major PM advantage as the SoC can hit retention during idle
> while still connected to the modem and getting notifications.
> 
> So looks like during idle we can keep USB in autosuspend mode with
> something like the below shell script function.

Yes, I should really start using serials instead of USB. But... I have
working ofono there, and was using that phone and am little short on
time at the moment.

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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