On Mon, Jan 19, 2015 at 5:20 AM, Alexandre Courbot <gnurou@xxxxxxxxx> wrote: > On Sat, Jan 17, 2015 at 1:49 AM, Sören Brinkmann <soren.brinkmann@xxxxxxxxxx> wrote: >> On Fri, 2015-01-16 at 12:11PM +0100, Johan Hovold wrote: >>> Implementing proper wakeup support for unclaimed GPIOs would take some >>> work (if at all desired), but that is not a reason to be adding custom >>> implementations that violates the kernel's power policies and new ABIs >>> that would need to be maintained forever. (...) >>> Meanwhile you can (should) use gpio-keys if you need to wake your system >>> on gpio events. >> >> We had that discussion and I don't think GPIO keys is the right solution >> for every use-case. > > Sorry, it has been a while - can you remind us of why? There are such cases. Of course keys should be handled by GPIO-keys and these will trigger the right wakeup events in such cases. This is for more esoteric cases: we cannot have a kernel module for everything people want to do with GPIOs, and the use case I accept is GPIOs used in automatic control etc, think factory lines or doors. We can't have a "door" driver or "punch arm" or "fire alarm" driver in the kernel. Those are userspace things. Still such embedded systems need to be able to go to idle and sleep to conerve power, and then they need to put wakeups on these GPIOs. So it is a feature userspace needs, though as with much of the sysfs ABI it is very often abused for things like keys and LEDs which is an abomination but we can't do much about it :( Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
