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

2014/1/15 Jean-Christophe PLAGNIOL-VILLARD [off-list ref]:

On 12:05 Mon 13 Jan     , Jean-Jacques Hiblot wrote:

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Hi Boris,

2014/1/13 boris brezillon [off-list ref]:

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On 13/01/2014 11:29, Jean-Jacques Hiblot wrote:

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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?

I even send a proposition to do this work across the kernel t the CE-Linux for
funding

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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.

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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.

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Best Regards,

Boris

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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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