Mark Brown wrote at Thursday, August 04, 2011 11:35 PM: > 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. Certainly. > > 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. True, but I think there are two cases: 1) Some code legitimately uses a pin as both a GPIO and IRQ, and is fully cognizant of the fact, just like in your example -> no bug. 2) Two pieces of unrelated code somehow accidentally get a GPIO and IRQ number that map to the same resource, e.g. due to incorrect board files or Device Tree content. This is probably a bug, but ends up looking exactly the same as far as the IRQ code's gpio_request call failing in the patch I posted. > 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? -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
