linux-kernel - Re: [PATCH v3 01/21] dt-bindings: i2c: eeprom: Document manufacturer used as generic fallback

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Date:   Wed, 19 Apr 2017 18:35:18 -0500
From:   Rob Herring <robh@...nel.org>
To:     Javier Martinez Canillas <javier@....samsung.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Simon Horman <horms@...ge.net.au>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Sekhar Nori <nsekhar@...com>,
        David Lechner <david@...hnology.com>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v3 01/21] dt-bindings: i2c: eeprom: Document manufacturer
 used as generic fallback

On Wed, Apr 19, 2017 at 6:27 PM, Rob Herring <robh@...nel.org> wrote:
> On Thu, Apr 13, 2017 at 10:04:25PM -0300, Javier Martinez Canillas wrote:
>> The at24 driver allows to register I2C EEPROM chips using different vendor
>> and devices, but the I2C subsystem does not take the vendor into account
>> when matching using the I2C table since it only has device entries.
>>
>> But when matching using an OF table, both the vendor and device has to be
>> taken into account so the driver defines only a set of compatible strings
>> using the "atmel" vendor as a generic fallback for compatible I2C devices.
>>
>> Document in the Device Tree binding document that this manufacturer should
>> be used as the generic fallback.
>>
>> Suggested-by: Wolfram Sang <wsa@...-dreams.de>
>> Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>
>>
>> ---
>>
>> Changes in v3: None
>> Changes in v2: None
>>
>>  Documentation/devicetree/bindings/eeprom/eeprom.txt | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/eeprom/eeprom.txt b/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> index 5696eb508e95..d0395f14e2b3 100644
>> --- a/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> +++ b/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> @@ -17,7 +17,8 @@ Required properties:
>>       "renesas,r1ex24002"
>>
>>        If there is no specific driver for <manufacturer>, a generic
>> -      driver based on <type> is selected. Possible types are:
>> +      driver based on <type> and manufacturer "atmel" is selected.
>> +      Possible types are:
>
> This isn't quite right. What the driver does isn't really relevant to
> the binding.
>
> These types with no vendor are used as the compatible string, so we have
> to allow them. But it should be clear that no vendor is deprecated.
> Ironically, it is a lot of Atmel boards that do this.
>
> We should also explicitly list what are valid manufacturers. We also
> have "at" as a vendor prefix which perhaps we should explicitly say is
> deprecated.

I should perhaps look at the rest of the series before replying..

Based on that, the only comment that applies is listing the
manufacturers that are valid. From a DT perspective, I should not have
to know what the OS driver supports. If the device is compatible with
atmel, then that is required. If not, then the specific manufacturer's
compatible alone is enough and the OS has to match to that.

Rob