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Message-ID: <554B86D5.8080403@hurleysoftware.com>
Date: Thu, 07 May 2015 11:37:57 -0400
From: Peter Hurley <peter@hurleysoftware.com>
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To: "Dr. H. Nikolaus Schaller" <hns@goldelico.com>,
        Mark Rutland <mark.rutland@arm.com>
CC: Pavel Machek <pavel@ucw.cz>,
        List for communicating with real GTA04 owners 
	<gta04-owner@goldelico.com>,
        NeilBrown <neil@brown.name>,
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        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        "grant.likely@linaro.org" <grant.likely@linaro.org>,
        Jiri Slaby <jslaby@suse.cz>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
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Subject: Re: [Gta04-owner] [PATCH 0/3] tty slave device support - version
 3.
References: <20150318055437.21025.13990.stgit@notabene.brown> <55492001.30806@hurleysoftware.com> <DE60E7AA-1BF4-4A68-9638-E09F85FD5C72@goldelico.com> <20150506092738.GB4508@amd> <A2594559-CA92-40C2-A06A-AC2483E85CB1@goldelico.com> <554A03A7.2000504@hurleysoftware.com> <D10E1092-E75F-48F7-86F1-F8987973CEB5@goldelico.com> <20150506123632.GA1764@leverpostej> <BD3D34DD-2FC8-44A2-89FA-35843065F50F@goldelico.com>
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On 05/06/2015 09:28 AM, Dr. H. Nikolaus Schaller wrote:

> The key point appears to be how we want to see the serial connection. Is the
> device connected to the uart or the uart to a device?
> 
> In OO terminology: „device connects to uart“ vs. „uart has device connected“.
> "d -> u“ vs. "u <- d“.

This is not a very good analogy because both relationships need to be
represented.

The practical consideration is the lifetime of the target device.
If the target device should/must have a lifetime (as viewed from the host)
outside that of the uart, then the target device should not be a slave device.

Object lifetime is controlled by expressions of ownership or scope.
Since devicetree offers no expression of ownership, scope is the
obvious and natural way to control lifetime.

Regards,
Peter Hurley