On Tue, Dec 16, 2014 at 6:57 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Monday 15 December 2014 13:35:47 Ray Jui wrote: >> >> Like I said previously, dynamic GPIO allocation works fine in the >> kernel, as long as all of our GPIO clients in the kernel use gpiod based >> API, which is what we will enforce going forward. The only problem is >> with some of our customers who use GPIO through sysfs and expect fixed >> global GPIO numbers. Thinking about this more, it's probably not that >> difficult to add a script for those customers to convert/map the GPIO >> numbers based on readings parsed from sysfs, so I guess that's fine. >> > > I think we discussed the user space interface a number of times > in the past, but I forgot the outcome. Either there is already > a way to name gpio lines uniquely in sysfs, or there should be > one. > > Can you reach the gpio interfaces using /sys/devices/0001234.bus/1234566.gpiocontroller/...? No, but it seems like this is exactly the solution we need. We could have an "export" node there that takes a relative GPIO number and exports it under /sys/devices/0001234.bus/1234566.gpiocontroller/exported/ the same way the current sysfs exporter does. Then for convenience we could also allow exported GPIOs to take names to be used under the shorter /sys/class/gpio/ (named GPIOs is another request we pushed back many times but that keeps coming). Let's see if I can come with a patch. That would at least give us something to reply to the many people that hit this issue. -- 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
