linux-kernel - Re: [PATCH] i2c: slave-eeprom: Add an OF device ID table

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Date:   Wed, 16 Aug 2017 11:36:25 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     linux-kernel@...r.kernel.org,
        Luis Oliveira <Luis.Oliveira@...opsys.com>,
        linux-i2c@...r.kernel.org
Subject: Re: [PATCH] i2c: slave-eeprom: Add an OF device ID table

Hello Wolfram,

On 08/14/2017 09:52 PM, Wolfram Sang wrote:
> On Wed, Aug 09, 2017 at 12:12:56PM +0200, Javier Martinez Canillas wrote:
>> The driver doesn't have a struct of_device_id table but supported devices
>> are registered via Device Trees as shown in the following DT binding doc:
>>
>> Documentation/devicetree/bindings/i2c/i2c-designware.txt
> 
> Uhhh, that needs to be fixed to something else! I don't think i2c slave
> functionality should be described in DT. The slave functionality is pure
> software, so IMO it doesn't match the "HW description" requirement.
>

Right, indeed.
 
>> But this works on the assumption that a I2C device registered via OF will
>> always match a legacy I2C device ID and that the MODALIAS reported will
>> always be of the form i2c:<device>.
>>
>> And this could change in the future so the correct approach is to have an
>> OF device ID table if the devices are registered via OF.
>>
>> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
> 
> Thanks for finding the issue, still NAK to this patch. Are you
> interested in updating the docs?
> 

What kind of change are you looking for? The example was introduced by commit
04606ccc84e3 ("i2c: designware: introducing I2C_SLAVE definitions") that says:

- A example was added to designware-core.txt Documentation that shows
  how the slave can be setup using DTS

So I could change this example to instead use a real EEPROM compatible (e.g:
"microchip,24c02") instead of "linux,slave-24c02". Would that be correct?

Best regards,
-- 
Javier Martinez Canillas
Software Engineer - Desktop Hardware Enablement
Red Hat