On Mon, Aug 8, 2022 at 1:41 PM Johannes Pointner <h4nn35.work@xxxxxxxxx> wrote: > > Hello, > > I just tried to upgrade a am335x based board from 5.10 LTS to 5.15 LTS > and this broke an application for me because the gpiochip numbering > changed: Don't we have somewhere in the documentation that the GPIO chip device name should be nothing except name. It seems to me you are relying on the name to be part of ABI, but it's not. The ABI is the real device behind no matter what name the associated character device has. To prevent objection, it's the same as for network cards (old) naming scheme when eth0 and eth1 can be swapped at boot time. > <= 5.10: > gpio0 == gpiochip0 > gpio1 == gpiochip32 > gpio2 == gpiochip64 > gpio3 == gpiochip96 > > > 5.10 > gpio0 == gpiochip96 > gpio1 == gpiochip0 > gpio2 == gpiochip32 > gpio3 == gpiochip64 > > This is the same for /dev/gpiochipX Sure. ... > Did I configure something wrong or do I have to adjust the devicetree > for the board somehow? No, you have to write the application based on `libgpiod` or so with proper handling of the GPIO chips. Note, that if you run `gpiodetect` you will see the device instance names for your GPIO chips (IIRC it's called 'label' in the Linux kernel inside APIs) which should be unique and that is what your application should rely on. -- With Best Regards, Andy Shevchenko
