On 09/23/2013 06:14 PM, Stephen Warren wrote: > On 09/22/2013 08:40 AM, Javier Martinez Canillas wrote: >> To use a GPIO pin as an interrupt line, two previous configurations >> have to be made: >> >> a) Map the GPIO pin as an interrupt line into the Linux irq space >> b) Enable the GPIO bank and configure the GPIO direction as input >> >> Most GPIO/IRQ chip drivers just create a mapping for every single >> GPIO pin with irq_create_mapping() on .probe so users usually can >> assume a) and only have to do b) by using the following sequence: >> >> gpio_request(gpio, "foo IRQ"); >> gpio_direction_input(gpio); >> >> and then request a IRQ with: >> >> irq = gpio_to_irq(gpio); >> request_irq(irq, ...); >> >> Some drivers know that their IRQ line is being driven by a GPIO >> and use a similar sequence as the described above but others are >> not aware or don't care wether their IRQ is a real line from an >> interrupt controller or a GPIO pin acting as an IRQ. >> ... > > I think that explanation is a bit like retro-actively implying that > drivers /should/ be aware of whether their IRQ is a GPIO or not, and > should be acting differently. However, they should not. > I know the patch description is rather verbose but since we have been discussing this a lot and people have different opinions I wanted to explain some context and the motivation for the patch. > I would much rather see a simpler patch description along the lines of: > > The OMAP GPIO controller HW requires that a pin be configured in GPIO > mode in order to operate as an interrupt input. Since drivers should not > be aware of whether an interrupt pin is also a GPIO or not, the HW > should be fully configured/enabled as an IRQ if a driver solely uses IRQ > APIs such as request_irq, and never calls any GPIO-related APIs. As > such, add the missing HW setup to the OMAP GPIO controller's irq_chip > driver. > Thanks for the suggestion, I'll use something like that when I do a proper post as a PATCH and not RFC. > The code change looks like it does what I would expect though. > Great, let's see what is the feedback from Santosh and Kevin about the implementation since they are the maintainers of this driver. I really hope we can find a solution to this long standing issue. Thanks a lot and best regards, Javier -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
