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

Hi,

On 11 May 2012 13:33, Josh Wu [off-list ref] wrote:

Hi, Javier


On 5/11/2012 5:13 PM, javier Martin wrote:

quoted

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.

quoted

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.

quoted

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.

quoted

Regards.

[1] http://lxr.linux.no/#linux+v3.3.4/drivers/gpio/gpio-pca953x.c#L495

-- 
Javier Martin
Vista Silicon S.L.
CDTUC - FASE C - Oficina S-345
Avda de los Castros s/n
39005- Santander. Cantabria. Spain
+34 942 25 32 60
www.vista-silicon.com
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