I2C eeprom compatibles? (was Re: [PATCH/RFC 03/19] ARM: shmobile: gose: add i2c2 bus to device tree)

[Geert Uytterhoeven]

On Mon, Dec 21, 2015 at 5:33 AM, Simon Horman <horms at verge.net.au> wrote:
> On Fri, Dec 18, 2015 at 11:32:15AM +0100, Wolfram Sang wrote:
>> On Fri, Dec 18, 2015 at 10:06:48AM +0100, Arnd Bergmann wrote:
>> > On Friday 18 December 2015 08:35:32 Wolfram Sang wrote:
>> > > >
>> > > > It seems to me that we have some consensus around:
>> > > >
>> > > >       compatible = "renesas,r1ex24002", "24c02";
>> > >
>> > > Thinking again, "generic,24c02" or "generic-24c02" could also be an
>> > > option.
>> > >
>> > > > Should this be added to Documentation/devicetree/bindings/eeprom/eeprom.txt ?
>> > > > Or documented elsewhere?
>> > >
>> > > Probably we need a DT maintainers advice here? I don't mind vendor
>> > > specific compatibles being documented, but I'm reluctant to add all
>> > > these compatibles for the myriads of I2C eeproms to the at24 driver. 99%
>> > > are covered by the generic case.
>> > >
>> > > Adding DT to CC.
>> >
>> > I'd rather use some vendor string in addition to 24c02. Isn't this originally
>> > an Atmel part? In that case, using "atmel,24c02" as the most generic string
>> > would be appropriate,
>>
>> Yeah, the at24 driver is named after Atmel chips AFAIR. Having "atmel,*"
>> as the generic fallback sounds like a good solution to me, too.
>>
>> > and IIRC the i2c framework will just match that with
>> > the "24c02" entry in the i2c_device_id list.
>>
>> True, although this behaviour is often complained about. There have been
>> attempts to make i2c/spi behave like the rest of the DT world and to
>> deprecate the current way. It didn't happen because of lots gory details,
>> however :/
>
> My reading of the above is that we are currently leaning towards:
>
>         compatible = "renesas,r1ex24002", "atmel,24c02";
>
> And we are unsure what to do about the documentation.

To avoid checkpatch.pl complaining about our DTS patches, "renesas,r1ex24002"
should be added to Documentation/devicetree/bindings/eeprom/eeprom.txt.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds