Re: [PATCH] input: add support for generic GPIO-based matrix keypad

[Eric Miao <eric.y.miao@gmail.com>]

On Thu, May 7, 2009 at 4:41 PM, Trilok Soni <soni.trilok@gmail.com> wrote:
> Hi Eric,
>
> On Thu, May 7, 2009 at 1:30 PM, Eric Miao <eric.y.miao@gmail.com> wrote:
>> Original patch by Marek Vasut, modified by Eric in:
>>
>> 1. use delayed work to simplify the debouncing
>> 2. build keycode array for fast lookup
>> 3. combine col_polarity/row_polarity into a single active_low field
>> (are there some cases where the GPIOs are externally connected
>> with an inverter and thus causing two different polarity requirement??)
>> 4. use a generic bit array based XOR algorithm to detect key press/release,
>> which should make the column assertion time shorter and code a bit
>> cleaner
>> 5. remove the ALT_FN handling, which is no way generic, the ALT_FN
>> key should be treated as no different from other keys, and translation
>> will be done by user space by commands like 'loadkeys'.
>>
>> Patch tested on Littleton/PXA310 (though PXA310 has a dedicate keypad
>> controller, I have to configure those pins as generic GPIO to use this
>> driver, works quite well, though ;-)
>
> Any support about removing/clearing ghost/phantom keys? Also we assume
> that all gpios in the matrix should be able to generate interrupts so
> no polldev support required.
>

Is there some info about such ghost/phantom keys? Otherwise I'll
assume these are something like sticky control keys?

I'm not sure if there're any such support in console tools and in
input subsystem. Hard to say...

And the comments below are of great value, I'll incorporate these
suggestions in later submission. Thanks very much.