Re: GPIO debounce problems on 3.2

[Kevin Hilman <khilman@ti.com>]

Grazvydas Ignotas <notasas@gmail.com> writes:

> On Mon, Jan 30, 2012 at 9:36 PM, Kevin Hilman <khilman@ti.com> wrote:
>> Grazvydas Ignotas <notasas@gmail.com> writes:
>>
>>> Hi,
>>>
>>> On 3.2 (I think some earlier versions too), with CONFIG_CPU_IDLE
>>> enabled GPIO based buttons are not working properly on OMAP3 pandora,
>>> button presses are almost never registered. The buttons are connected
>>> GPIO bank4 and have hardware debounce feature enabled.
>>>
>>> Doing either of the following solves (or hides) the problem:
>>> - disabling CPU_IDLE in kernel config
>>> - disabling debounce for the buttons
>>> - running a program spinning a loop on the CPU
>>>
>>> From what I can see in the code debounce clock is disabled when
>>> entering idle, can those GPIOs work without debounce clock?
>>
>> Yes, the clock is only for the debounce feature, but the GPIOs are
>> capable of wakeups and interrupts with the debounce clock disabled.
>
> Hmm but it doesn't work here (OMAP3530 ES2.1), /proc/interrupts
> doesn't increase when I hit buttons unless something else is happening
> at the same time. I wonder if I'm missing something here, does it all
> work for you with debounce on? 

Yes.  

Specifically, I tested on a n900 which has several GPIOs in the board
file (board-rx51.c) with debounce enabled.

When I push the button (or slide the switch in this case), I see
/proc/interrupts incrementing on an idle system with CPUidle enabled.

The same GPIOs can also bring the system out of suspend (debounce clocks
are disabled on suspend also.)

Kevin