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

[Bo Shen <voice.shen@atmel.com>]

Hi Javier,

On 5/11/2012 20:47, javier Martin wrote:
> 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.

There is no need to change the driver of QT1070. Please try the 
suggestion of Dmitry. Using the irq_set_irq_type() to set the trigger 
mode of the GPIO.

>
>>> 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
>
>
>