From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Lawnick Subject: Re: [PATCH] i2c: Make I2C ID tables non-mandatory for DT'ed and/or ACPI'ed devices Date: Wed, 04 Jun 2014 08:09:31 +0200 Message-ID: <538EB81B.3090807@gmx.de> References: <1401452797-29521-1-git-send-email-lee.jones@linaro.org> <1401452797-29521-2-git-send-email-lee.jones@linaro.org> <20140530123656.GC2742@katana> <20140530133405.GB29731@lee--X1> <20140530174800.GA4917@katana> <20140530192516.GA4319@lee--X1> <20140531134805.GA3287@katana> <538C8A59.2070907@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Linus Walleij Cc: Wolfram Sang , Grant Likely , Lee Jones , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-i2c@vger.kernel.org" List-Id: linux-i2c@vger.kernel.org Am 03.06.2014 13:18, schrieb Linus Walleij: > On Mon, Jun 2, 2014 at 4:29 PM, Michael Lawnick 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. The eeprom contains a device tree that is dynamically merged. KR Michael From mboxrd@z Thu Jan 1 00:00:00 1970 From: ml.lawnick@gmx.de (Michael Lawnick) Date: Wed, 04 Jun 2014 08:09:31 +0200 Subject: [PATCH] i2c: Make I2C ID tables non-mandatory for DT'ed and/or ACPI'ed devices In-Reply-To: References: <1401452797-29521-1-git-send-email-lee.jones@linaro.org> <1401452797-29521-2-git-send-email-lee.jones@linaro.org> <20140530123656.GC2742@katana> <20140530133405.GB29731@lee--X1> <20140530174800.GA4917@katana> <20140530192516.GA4319@lee--X1> <20140531134805.GA3287@katana> <538C8A59.2070907@gmx.de> Message-ID: <538EB81B.3090807@gmx.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am 03.06.2014 13:18, schrieb Linus Walleij: > On Mon, Jun 2, 2014 at 4:29 PM, Michael Lawnick 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. The eeprom contains a device tree that is dynamically merged. KR Michael