[PATCH 3/8] i2c: at91: use an id table for SoC dependent parameters

Nicolas Ferre nicolas.ferre at atmel.com
Mon Sep 3 03:51:18 EDT 2012

On 09/03/2012 09:24 AM, ludovic.desroches :
> Le 09/01/2012 11:10 AM, Jean-Christophe PLAGNIOL-VILLARD a écrit :
>> On 22:47 Fri 31 Aug     , Sylwester Nawrocki wrote:
>>> On 08/31/2012 04:51 PM, Nicolas Ferre wrote:
>>>>>> diff --git a/arch/arm/mach-at91/at91rm9200.c
>>>>>> b/arch/arm/mach-at91/at91rm9200.c
>>>>>> index f2112f9..0bc91e5 100644
>>>>>> --- a/arch/arm/mach-at91/at91rm9200.c
>>>>>> +++ b/arch/arm/mach-at91/at91rm9200.c
>>>>>> @@ -187,7 +187,7 @@ static struct clk_lookup
>>>>>> periph_clocks_lookups[] = {
>>>>>>        CLKDEV_CON_DEV_ID("pclk", "ssc.0",&ssc0_clk),
>>>>>>        CLKDEV_CON_DEV_ID("pclk", "ssc.1",&ssc1_clk),
>>>>>>        CLKDEV_CON_DEV_ID("pclk", "ssc.2",&ssc2_clk),
>>>>>> -    CLKDEV_CON_DEV_ID(NULL, "at91_i2c",&twi_clk),
>>>>>> +    CLKDEV_CON_DEV_ID(NULL, "at91rm9200_i2c",&twi_clk),
>>>>> use i2c-xxx as on other drivers
>>>>> and I do not like to have platform_device_id
>>>> Me, I like it and find this implementation very elegant.
>>>>> as we need to touch the driver to add a new soc
>>>> So what? We still keep the compatibility if the new SoC has it
>>>> compatibility assured with previous revision: there is nothing to
>>>> modify.
>>> I agree. The driver would need to be touched to support new SoC only if
>>> the IP there have had some differences, which would have needed to be
>>> resolved anyway.
>>>>> please use platform data
>>> Using platform data for the dt platforms would have been more
>>> troublesome,
>>> wouldn't it ? I like Ludovic's approach which handles both: dt and
>>> non-dt
>>> cases in uniform way from the driver's POV.
>> no you will describe it via DT as done on all the other drivers
>>>> No, it does not have to be exposed to the user: these data are highly
>>>> dependent on the actual hardware (IP revision in fact). So, no need to
>>>> mess with platform data.
>> no I really see no point on these list of platform_id it's does not
>> look more
>> nice just more huggly to have x names. This is at the end the same as
>> passing
>> platform data via soc info (add_xx or dtsi)
>> And here you just do the same as cpu_is via names.
>> The driver need to read IP revision instead
> At the beginning it was planned to do this but:
> - a new SoC, with a new IP version lead to update the driver also
> - with the MCI driver which uses IP version, I have some cases where
> using the version was not enough, a SoC approach would be better. For
> instance, the IP version tells that we can use PDC feature but PDC is
> not connected.

Absolutely. Nikolaus and you have summarized clearly the situation.

I think there is a consensus here.

So, we can move to a v2 patch series...

Nicolas Ferre

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