[OpenWrt-Devel] [PATCH] gpio-button-hotplug: gpio-keys: read initial state

[David Bauer]

Hello Linus,

On 15.06.19 10:26, Linus Walleij wrote:
> Without any detailed knowledge I'd say the most common cause
> is the underlying GPIO chip implementation. There are often transient
> line events when the system is powered up and initialized and it
> is often necessary for the gpio_chip driver to clear any interrupt
> flags in hardware before setting up the gpio chip, especially the
> irqchip portions of it.
> 
> I tried to half-guess what gpio chip this is using and since it
> is WiFi pro 1200e I guess ths gpio driver is
> drivers/gpio-ath79.c which does indeed initialize an
> irqchip without clearing the interrupts first.
> 
> Can you try this patch, if this solves the problem I will commit
> it upstream as well:

Thanks for your patch. I've tested it on my device but sadly, i still
see the ghost presses.

It seems the input is indeed not stable after setting the GPIO
direction. With the following patch applied, i get zero ghost presses
and the buttons work as expected. However I'm not sure if this approach
is the right one to fix the underlying issue.