[Letux-kernel] Dual-edge GPIO IRQs (Re: SMP issue between LX16 and LX20 found...)

[Paul Boddie]

On Sunday, 15 June 2025 21:38:40 CEST H. Nikolaus Schaller wrote:
> 
> I think for the LX16 we have exactly the same. But there is special code to
> handle dual-egde in the x1600 pinctl driver for interrupts (toggling the
> edge after each interrupt).

I found code in ingenic_gpio_irq_ack and in ingenic_gpio_irq_set_type that 
converts a dual-edge interrupt configuration into a dynamic level-based 
configuration.

Looking at the gpio-keys driver, it seems that "wakeup-source" is required in 
the device tree node for the wakeup button. I also added the following:

  wakeup-event-action = <EV_ACT_ASSERTED>;

What I see is that during normal operation, the wakeup button produces lots of 
interrupts, which I understand is not very desirable. However, when shut down, 
if I just hold down the wakeup button, the system starts up without me 
releasing it. But I imagine that it is when the system is suspended, not shut 
down, that this behaviour is desired.

Looking more closely at the driver, it seems that the dual-edge configuration 
is only selected in gpio_keys_button_disable_wakeup. I can't say I really 
understand what is supposed to happen.

Paul