Re: [PATCH] Input: gpio_keys: Add level trigger support for GPIO keys

[Andy Shevchenko]

On Fri, Feb 9, 2018 at 11:23 AM, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
> On 9 February 2018 at 14:39, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
>> On Thu, Feb 8, 2018 at 10:08 PM, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
>>> On some platforms (such as Spreadtrum platform), the GPIO keys can only
>>> be triggered by level type.
>>
>> How do you stop the interrupt from re-triggering as long as the key
>> stays pressed?
>
> We will set the level type irq handler as handle_level_irq(), in this
> function, it will mask and ack the irq firstly.

Wouldn't be ambiguous?

1. User presses the key ->
  a) we got edge followed by level signaling;
  b) IRQ core masks line, calls handler, ACKs, unmasks;
  c) somewhere here Press Event is sent;
  d) we still have level... We get IRQ fired again? But see 1. It
obviously not the case.
2. User releases the key ->
  ...

So, the main question if I understood Dmitry correctly is the period
in time where IRQ line should be masked on one hand, and on the other
it will guarantee that user didn't release-press cylcle.

-- 
With Best Regards,
Andy Shevchenko