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

[Grygorii Strashko <grygorii.strashko@ti.com>]

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.

-- 
regards,
-grygorii

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