[rtc-linux] Re: [PATCH] rtc: omap: Support ext_wakeup configuration

[Marcin Niestroj <m.niestroj@grinn-global.com>]

Hi,

On 08.04.2016 19:16, Grygorii Strashko wrote:
> On 04/08/2016 06:14 PM, Tony Lindgren wrote:
>> * Grygorii Strashko <grygorii.strashko@ti.com> [160408 03:41]:
>>> Hi Tony,
>>>
>>> On 04/05/2016 01:40 AM, Tony Lindgren wrote:
>>>> Hi,
>>>>
>>>> * Marcin Niestroj <m.niestroj@grinn-global.com> [160404 08:57]:
>>>>> Support configuration of ext_wakeup sources. This patch makes it
>>>>> possible to enable ext_wakeup and set it's polarity, depending on board
>>>>> configuration. AM335x's dedicated PMIC (tps65217) uses ext_wakeup to
>>>>> notify about power-button presses. Handling power-button presses enables
>>>>> to recover from RTC-only power states correctly.
>>>>
>>>> I suggest you just set this pin up as a minimal gpiochip. That way
>>>> we can use the standard binding :) And if we get lucky, this pin can
>>>> also trigger during runtime.
>>>>
>>>
>>> Following my comments on v2 of this patch I propose to rollback to
>>> this version of the patch.
>>>
>>> It seems doesn't fit in gpiochip, it's more likely irqchip, but since
>>> rtc can't generate IRQ there are nor reasons for these genetic
>>> experiments and RTC's specific bindings looks more suitable, at least for me.
>>
>> Hmm well gpiochips typically are irqchip too. IMO the generic binding
>> here sounds like "gpio-wakeup" as it's an input with polarity and with
>> an optional interrupt.
>>
>> Plain irqchip would work too in this case if there are no other GPIO
>> specific features. Some other RTCs may have more GPIO like features.
>>
>> In any case, setting the ext_wakeup up as an irqchip means that the
>> RTC controller can be used as a dedicated wakeirq with Linux :)
>
> It can't :( It can't generate IRQ when state of ext_wakeup line has
> been changed.
>
>>
>> Are you guys sure there's no wake pin events during runtime? AFAIK
>> the RTCs just typically produce an interrupt when programmed to
>> do so, they don't know the state of the SoC.
>>
>
> I do not think that It can be fit in gpiochip or irqchip -
> in my opinion right way is to proceed with bindings proposed by
> Marcin in this patch v1.
>
> But, probably, it could fit in pinctrl:
> - this is pin's configuration
> - this is one-time configuration
> - or - configuration which can be applied before suspend
>    and resorted after suspend.
>
> if you still wanna try some generic framework.
>

pinctrl bindings looks ok for our use case (enable/disable input,
configure debounce), except I don't see any way to pass polarity
(active low/high) to the driver.

-- 
Marcin Niestroj

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