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

* Grygorii Strashko [off-list ref] [160408 10:17]:

On 04/08/2016 06:14 PM, Tony Lindgren wrote:

quoted

* Grygorii Strashko [off-list ref] [160408 03:41]:

quoted

Hi Tony,

On 04/05/2016 01:40 AM, Tony Lindgren wrote:

quoted

Hi,

* Marcin Niestroj [off-list ref] [160404 08:57]:

quoted

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.

Hmm to me it certainly seems it should be capable of generating and RTC
interrupt as we have EXT_WAKEUP_STATUS register containing four bits,
one for each wakeup line.

We also have EXT_WAKEUP_DB_EN for debounce, EXT_WAKEUP_POL for polarity,
and EXT_WAKEUP_EN to enable in addition to status.. These certainly make
it look like a gpiochip or irqchip.

quoted

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.

Yeah the pin certainly should be configured by pinctrl if it is
muxable.

However, the functionality of the pin is clearly tied to the RTC
driver. My guess the reason it does not generate interrupts is that
it's status needs to be cleared each time it triggers? That fits the
irq mask/unmask for generic wakeirq like we do for the padconf.

Sounds like some experiments and reasoning is needed :) I guess the
first test to run is tools/testing/selftests/timers/rtctest.c to
make sure the RTC interrupts trigger properly.

Regards,

Tony
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