Re: [RFC] QT1070: change the trigger mode of QT1070

[javier Martin <javier.martin@vista-silicon.com>]

Hi,

On 11 May 2012 13:33, Josh Wu <josh.wu@atmel.com> wrote:
> Hi, Javier
>
>
> On 5/11/2012 5:13 PM, javier Martin wrote:
>
>> Hi all,
>> let's take a chip which presents a similar issue like the pca953x [1].
>> This chip has an IRQ line that is meant to be connected to a SoC input
>> like the qt1070.
>>
>> The flags that are used for pca953x are: (IRQF_TRIGGER_LOW | IRQF_ONESHOT)
>>
>> Can't we do the same for qt1070?
>
>
> I did a simple test in my board in 2.6.39,  This flag doesn't work. But
> IRQF_TRIGGER_FALLING works fine.
> So the question is what is different between this flag with
> IRQF_TRIGGER_FALLING?

I don't know but IRQF_TRIGGER_FALLING works for me too.

>> And even more important, can you give me an example of an architecture
>> in mainline which cannot support these irq flags and still be able to
>> detect a change from high to low in a GPIO as qt1070 requires?
>
>
> For now, AT91SAM9M10 can only detect GPIO input change, it cannot tell is
> falling or rising. So in theory it cannot support falling flags.
> The strange thing is, currently we use IRQF_TRIGGER_NONE in 2.6.39 kernel
> for both AT91SAM9M10 and 9X5 chips, and they all work fine. So I need check
> the code of GPIO part.
>
>
>>
>> Moreover, if you try a grep for IRQ_TRIGGER_NONE in the kernel tree
>> you won't find any driver doing this strange thing.
>>
>> Do you agree at least that we must change IRQ_TRIGGER_NONE flag into a
>> more sensible choice?
>
>
> Yes. I agreed.
>
>>
>> Regards.
>>
>> [1] http://lxr.linux.no/#linux+v3.3.4/drivers/gpio/gpio-pca953x.c#L495




-- 
Javier Martin
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