On Thu, Aug 04, 2011 at 08:53:34PM -0700, Stephen Warren wrote:

Well, things break. This is essentially the problem I was describing in
the PATCH 0 email, just with a slightly different motivation.

There's a bunch of existing code using that idiom.

I suppose that an alternative here would be to simply ignore any errors
from gpio_request. This might have the benefit of removing the need for
the other two patches I posted in the series. However, it seems a little
dirty; one benefit of the IRQ code calling gpio_request and honoring
errors would be to detect when some completely unrelated code had a bug
and had called gpio_request on the GPIO before. Such detection would be
non-existent if we don't error out on gpio_request. Perhaps some mechanism
is needed to indicate that the driver has explicitly already called
gpio_request for a legitimate shared purpose, and only then ignore
errors?

But it's not a bug to use a GPIO as an IRQ source, otherwise we wouldn't
have gpio_to_irq() in the first place.  Feels like we need a backchannel
between gpiolib and the IRQ code to do this.  Or perhaps the drivers
that implement this should be taking care of setting up the GPIO mode?