device-tree: at91: irq and gpios: problem while requesting a gpio used as an interrupt source.

[Jean-Christophe PLAGNIOL-VILLARD]

On 14:04 Wed 15 Jan     , Jean-Jacques Hiblot wrote:
> 2014/1/15 Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>:
> > On 12:05 Mon 13 Jan     , Jean-Jacques Hiblot wrote:
> >> Hi Boris,
> >>
> >> 2014/1/13 boris brezillon <b.brezillon at overkiz.com>:
> >> > On 13/01/2014 11:29, Jean-Jacques Hiblot wrote:
> >> >>
> >> >> Hello Nicolas, Jean-Christophe,
> >> >>
> >> >> As I was trying to enable the touchscreen on the at91sam9261ek with
> >> >> device-tree support, I ran into an issue. The touchscreen driver needs
> >> >> to know the state of the pendown gpio and also needs it as an
> >> >> interrupt source.
> >> >>
> >> >> The problem is that when a gpio is used as an interrupt, it's
> >> >> requested by the pinctrl driver during the xlate stage, marking it
> >> >> unavaliable for the other driver.
> >> >> It looks like the at91 pinctrl driver is the only one to use
> >> >> gpio_request() in the xlate stage. Maybe we should remove this:
> >> >
> >> >
> >> > You should only request it as a GPIO and then use gpio_to_irq to get the
> >> > related IRQ.
> >> > Because what is done here, is to solve the case where only the irq
> >> > is request, and in this specific case we need to request the pin as a
> >> > GPIO.
> >> >
> >>
> >> That's what I did first, and was about to submit the patch for the
> >> touchscreen driver.
> >> However it doesn't feel right. Being able to get the state of a gpio
> >> that is also an interrupt seems very useful to me, not only for a
> >> touchscreen controller.
> >>
> >> I understand why it's being done here. It's a matter of being sure
> >> that the GPIO is an input and that it'll not be configured otherwise
> >> latter.
> >> But:
> >> 1) I'm wondering why the atmel pinctrl is the only one to do that.
> >
> > because this the only to start to do it right
> > I had a very long discussion woth LinusW and Grant the Gpio need to stop to
> > use gpio_to_irq & co for irq.
> How can you get the value of the gpio that is also an interrupt source then ?
> Can you give a short example?

you just have to check the irq source

failing or raising

but on 9261 impossible the gpio does not have such detail

but anyway this is the invert you need to get the information from the IRQ no the way
arround

so the gpio driver may need to be updated to provide such information to the
touch driver

Best Regards,
J.
> 
> >
> > I even send a proposition to do this work across the kernel t the CE-Linux for
> > funding
> >> 2) I believe that configuration of the direction can be done by
> >> describing the GPIO in the DT. (pinctrl-at91.c line 592).
> > No pinctrl is for pinmux ONLY not gpio direction & co
> >
> > Best Regards,
> > J.
> >
> >> 3) If all the GPIOs are described in the DT with a proper pinmux
> >> description, i believe the exclusion is also handled. It's probably
> >> not the case today though.
> >
> >>
> >> >
> >> > Best Regards,
> >> >
> >> > Boris
> >> >
> >> >>
> >> >> diff --git a/drivers/pinctrl/pinctrl-at91.c
> >> >> b/drivers/pinctrl/pinctrl-at91.c
> >> >> index a7549c4..cf91a35 100644
> >> >> --- a/drivers/pinctrl/pinctrl-at91.c
> >> >> +++ b/drivers/pinctrl/pinctrl-at91.c
> >> >> @@ -1463,14 +1463,6 @@ static int at91_gpio_irq_domain_xlate(struct
> >> >> irq_domain *d,
> >> >>          *out_hwirq = intspec[0];
> >> >>          *out_type = intspec[1] & IRQ_TYPE_SENSE_MASK;
> >> >>
> >> >> -       ret = gpio_request(pin, ctrlr->full_name);
> >> >> -       if (ret)
> >> >> -               return ret;
> >> >> -
> >> >> -       ret = gpio_direction_input(pin);
> >> >> -       if (ret)
> >> >> -               return ret;
> >> >> -
> >> >>          return 0;
> >> >>   }
> >> >>
> >> >> Jean-Jacques
> >> >
> >> >
> >>
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