Date: Mon, 20 Oct 2014 10:33:45 +0200
From: Andreas Werner <andreas.werner@men.de>
To: Wolfram Sang <wsa@the-dreams.de>
CC: Andreas Werner <andreas.werner@men.de>, <gregkh@linuxfoundation.org>,
        <linux-kernel@vger.kernel.org>, <linux-i2c@vger.kernel.org>,
        <johannes.thumshirn@men.de>
Subject: Re: [PATCH 1/2] drivers/misc/eeprom/men_eeprod: Introduce MEN Board
 Information EEPROM driver
Message-ID: <20141020083344.GA523@awelinux>
References: <cover.1413416105.git.andreas.werner@men.de>
 <d169930cfe45d4c05c79f7dd00471d732441529d.1413416105.git.andreas.werner@men.de>
 <20141016085835.GA1273@katana>
 <20141016102126.GB23256@awelinux>
 <20141016095910.GC1273@katana>
 <20141016114401.GA22506@awelinux>
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On Thu, Oct 16, 2014 at 01:44:02PM +0200, Andreas Werner wrote:
> On Thu, Oct 16, 2014 at 11:59:10AM +0200, Wolfram Sang wrote:
> > * PGP Signed by an unknown key
> > 
> > 
> > > I do not want to parse the things in userspace because this EEPROM data
> > > are related to the hardware and i want to give our customer the easiest way
> > > to access the data without installing any tool.
> > 
> > I understand that point of view. From an upstream point of view, things
> > may look different, though.
> > 
> 
> I also understand your point of view :-).
> Most customers wants just to have a running system without installing anything.
> And for me an EEPROM is so simple and should not need a complicated way
> to access it.
> 
> > > The current state to read the eeprom data is, that customer needs to install a big
> > > environment where the tool is integrated to have access to those kind of simple
> > > data or they have to write their own code.
> > 
> > i2cget from i2c-tools? You could do a simple shell script to parse the
> > data. Or do a board specific hook which reads the data and prints it to
> > the logfiles...
> > 
> 
> Yes of course there are a lot of possibilities. This was just an example
> what we currently use and what was developed years ago.
> 
> With a driver like this you can also define read only attributes to prevent customer
> to write or modify the data in the production section. With i2ctools you can just
> write any data to it you want.
> 
> > > > Consider how bloated the sysfs-ABI might get if every vendor who uses an
> > > > eeprom wants to expose the data this way?
> > > > 
> > > 
> > > Yes and no. The possible sysfs entries gets bloated if every vendor will do it
> > > like this way, but normally there is just one Board EEPROM on the board, therefore
> > > only one driver gets loaded.
> > 
> > I am not talking about runtime here, I don't care about that. I am
> > talking about the ABI we create and we have to maintain basically
> > forever. And with vendor specific configuartion data I have doubts with
> > that being stable.
> > 
> 
> Ok, but i do not think that we can make a "general" ABI definition for those kind
> of devices because every vendor will have its own data in the EEPROM which he want
> to have.
> 
> > > I mean its the same for every i2c device like a temperature sensor, I can also
> > > read it from userspace without any special hwmon driver.
> > 
> > These is a HUGE difference. If I read tempX_input, I don't need to care
> > if the sensor is I2C or SPI or whatever. The kernel abstracts that away.
> > The files you create are for your I2C EEPROM only. Data gets
> > "reformatted" and access gets hidden, but nothing is abstracted away.
> > It would be different if we had a generic convention for "serial_id" or
> > stuff like that. But as configuration data is highly specific I don't
> > see this coming.
> > 
> 
> For a standard sysfs interface it is a huge difference yes. At the point
> of few from the EEPROM device it is a device like a temp sensor which
> could be different from vendor to vendor.
> 
> Regards
> Andy
>

Greg what do you think about that driver as a Maintainer of the sysfs?
To we have other ways to get those kind of drivers in the mainline kernel?

Regards
Andy

 
> > 
> > * Unknown Key
> > * 0x14A029B6
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