Messages in this thread | | | From | Stephen Warren <> | Date | Thu, 4 Aug 2011 21:05:01 -0700 | Subject | RE: [PATCH 1/3] irq: If an IRQ is a GPIO, request and configure it |
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Rob Herring wrote at Thursday, August 04, 2011 7:55 PM: > On 08/04/2011 06:00 PM, Stephen Warren wrote: > > Many IRQs are associated with GPIO pins. When the pin is used as an IRQ, > > it can't be used as anything else; it should be requested. Enhance the > > core interrupt code to call gpio_request() and gpio_direction_input() for > > any IRQ that is also a GPIO. This prevents duplication of these calls in > > each driver that uses an IRQ. ... > > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c ... > > @@ -978,6 +979,16 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) > > old = *old_ptr; > > } while (old); > > shared = 1; > > + } else { > > + gpio = irq_to_gpio(irq); > > If you read the documentation for gpio, it is not recommended to use > irq_to_gpio. There's only a handful of users. Part of the problem is it > is platform specific and the gpio core cannot convert irq to gpio > number
It seems like that's a soluble problem though?
I was thinking about adding a to_gpio function to struct irq_chip, as the inverse of struct gpio_chip's to_irq. Then, presumably any platform would be able to convert back from IRQ to GPIO, provided the platform called a new __irq_to_gpio from the platform-specific gpio_to_irq, just like most gpio_to_irq implementations defer to __gpio_to_irq.
I ended up not doing that in this patchset, since Tegra's gpio_to_irq function already works for the IRQs/GPIOs that were relevant for my testing, and I wanted to post a simple patch first to driver discussion.
> Here is the relevant section: > > Non-error values returned from irq_to_gpio() would most commonly be used > with gpio_get_value(), for example to initialize or update driver state > when the IRQ is edge-triggered. Note that some platforms don't support > this reverse mapping, so you should avoid using it.
-- nvpublic
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