Re: [PATCH 3/5] gpio/omap: Add DT support to GPIO driver

[Javier Martinez Canillas <martinez.javier@gmail.com>]

On Sun, Apr 14, 2013 at 10:53 PM, Linus Walleij
<linus.walleij@linaro.org> wrote:
> On Sun, Apr 14, 2013 at 3:35 AM, Javier Martinez Canillas
> <martinez.javier@gmail.com> wrote:
>
>> Is the following inlined patch [1] what you were thinking that would
>> be the right approach?

Hi Linus, thanks a lot for your feedback.

>
> This looks sort of OK, but I'm still struggling with the question of
> what we could do to help other implementations facing the same issue.
>

Yes, I don't know how we can make it easier to other implementations
(besides adding the irq_request hook to irq_chip) since the logic is
GPIO controller specific.

For example I took a look to drivers/gpio/gpio-tegra.c and if I
understood correctly, the implementation for this driver should be
something like this:

diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
index 414ad91..a2d5c3d 100644
--- a/drivers/gpio/gpio-tegra.c
+++ b/drivers/gpio/gpio-tegra.c
@@ -346,6 +346,11 @@ static int tegra_gpio_wake_enable(struct irq_data
*d, unsigned int enable)
 }
 #endif

+static int tegra_gpio_irq_request(struct irq_data *d)
+{
+	tegra_gpio_request(NULL, d->hwirq);
+}
+
 static struct irq_chip tegra_gpio_irq_chip = {
 	.name		= "GPIO",
 	.irq_ack	= tegra_gpio_irq_ack,
@@ -355,6 +360,7 @@ static struct irq_chip tegra_gpio_irq_chip = {
 #ifdef CONFIG_PM_SLEEP
 	.irq_set_wake	= tegra_gpio_wake_enable,
 #endif
+	.irq_request    = tegra_gpio_irq_request,
 };

 static const struct dev_pm_ops tegra_gpio_pm_ops = {

This is definitely quite similar to the omap-gpio.c change but not the same.

> This is a pretty hard design pattern to properly replicate in every such
> driver is it not?
>
> Hmmmm
>

Is indeed a hard design pattern but I couldn't figure out a more
generic way to handle this.

Maybe we could use [1] for now to solve the issue that we have with
OMAP GPIO and later when the same issue is found on other GPIO
controllers and a similar change is made on these drivers we will see
some form of pattern that emerge allowing us to make a later refactor
to reduce the code duplication.

Or do you have a better idea on how to solve this?

> Yours,
> Linus Walleij

Best regards,
Javier