Re: [PATCH 1/2] gpio: dwapb: Use human understandable gpio numbering.

[Michael van der Westhuizen <michael@xxxxxxxxxxxxxxxx>]

> On 02 Jul 2015, at 5:02 PM, Michael van der Westhuizen <michael@xxxxxxxxxxxxxxxx> wrote:
> 
> 
>> On 02 Jul 2015, at 4:54 PM, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:
>> 
>> On 07/02/2015 05:21 PM, Richard Cochran wrote:
>>> On Thu, Jul 02, 2015 at 04:30:47PM +0200, Sebastian Andrzej Siewior wrote:
>>>> On 07/02/2015 04:26 PM, Richard Cochran wrote:
>>>>> On Thu, Jul 02, 2015 at 09:36:22AM +0200, Sebastian Andrzej Siewior wrote:
>>>>>> If you are in a specific SoC you could do
>>>>>> 	base = of_alias_get_id(np, "gpio") * num_of_gpio_per_chip
>>>>>> and get consistent numbers / sane.
>>>>> 
>>>>> And what about /sys/class/gpio ?
>>>> 
>>>> What about it?
>>> 
>>> The poor users of that interface cannot use "of_alias_get_id" as you suggest.
>> 
>> You do that in the driver. The only problem with that is that the
>> synopsys controller can have between one and four banks and a bank can
>> have 1-32 GPIOs if I remember correctly. That means you can't have a
>> static number of GPIOs like others do.
> 
> This is correct.
> 
>> Therefore I think a starting property is the only way and I would
>> prefer a generic one.
> 
> I would prefer a generic property too.  I was rather surprised that one did not exist.

… looking into this more closely, by the time we get into gpiochip_add there’s no notion
of the DT node that is associated to the gpiochip being added (and the gpiochip->dev
points to the parent device, which is the generally the parent DT node), so this can’t be
done generically without at least some churn in the individual drivers.

Michael--
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