linux-kernel - Re: [PATCH] i2c: Make I2C ID tables non-mandatory for DT'ed and/or ACPI'ed devices

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Message-ID: <CACRpkdbo9_xo6j7JBcjiuk6eYkqyaeMYLFsH3VczxotOmVRh1Q@mail.gmail.com>
Date:	Tue, 3 Jun 2014 13:18:15 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Michael Lawnick <ml.lawnick@....de>
Cc:	Wolfram Sang <wsa@...-dreams.de>,
	Grant Likely <grant.likely@...aro.org>,
	Lee Jones <lee.jones@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: Re: [PATCH] i2c: Make I2C ID tables non-mandatory for DT'ed and/or
 ACPI'ed devices

On Mon, Jun 2, 2014 at 4:29 PM, Michael Lawnick <ml.lawnick@....de> wrote:
> Am 02.06.2014 14:16, schrieb Linus Walleij:

>> Is this really so useful on embedded systems?
>>
>> I was under the impression that this method was something used
>> on say PC desktops with temperature monitors and EEPROMs
>> on some I2C link on the PCB, usage entirely optional and fun
>> for userspace hacks.
>>
> We use it for dynamic instantiating whole subsystems with multiplexers,
> sensors, controllers in an embedded system. The device list is taken from an
> I2C eeprom which gets read on hotplug.

Does this mean that you have stored the names (strings) that are used
by the Linux kernel for identifying the devices into your EEPROM?

That means that you have made the kernel-internal device driver names
an ABI which is unfortunate :-/

This is one of the reasons to why we insist on device tree: OS neutral
hardware description.

Yours,
Linus Walleij
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