Re: [PATCH v1 1/3] gpio: defer probe if pinctrl cannot be found

[Rob Herring]

On Thu, Jul 2, 2015 at 3:59 AM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> Hi Rob,
>
> On Wed, Jul 1, 2015 at 7:36 PM, Rob Herring <robherring2@xxxxxxxxx> wrote:
>> On Wed, Jul 1, 2015 at 7:45 AM, Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx> wrote:
>>> When an OF node has a pin range for its GPIOs, return -EPROBE_DEFER if
>>> the pin controller isn't available.
>>>
>>> Otherwise, the GPIO range wouldn't be set at all unless the pin
>>> controller probed always before the GPIO chip.
>>>
>>> With this change, the probe of the GPIO chip will be deferred and will
>>> be retried at a later point, hopefully once the pin controller has been
>>> registered and probed already.
>>
>> This will break cases where the pinctrl driver does not exist, but the
>> DT contains pinctrl bindings. We can have similar problems already
>> with clocks though. However, IMO this problem is a bit different in
>> that pinctrl is more likely entirely optional while clocks are often
>> required. You may do all pin setup in bootloader/firmware on some
>> boards and not others. Of course then why put pinctrl in the DT in
>> that case? They could be present just due to how chip vs. board dts
>> files are structured.
>
> Isn't that already the case?
> If I change the compatible value of a pinctrl node to an invalid value, I get:
>
>     sh-sci e6c50000.serial: could not find pctldev for node
> /pfc@e6050000/serial1, deferring probe

I guess so.

>> We could address this by simply marking the pin controller node
>> disabled. However, ...
>
> Doesn't seem to make any difference.

No doubt. I'm proposing that it should, not that it does already. Of
course, the callers will also have to test for -ENODEV and ignore
those errors.

Rob
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