2018-01-26 14:16 GMT+01:00 Timur Tabi [off-list ref]:

On 1/26/18 7:01 AM, Linus Walleij wrote:

quoted

This is a feature not a bug. It encourages people not to
depend on the global GPIO numberspace.

Just set it to -1.

If I change it to -1, then I think I'm going to break every existing MSM
platform that depends on the base address being 0, because then every MSM
driver will have a non-zero base, and none of the existing drivers register
more than one GPIO device.

So how about this:

        static int base = 0;

        chip->base = base;
        base = -1;

This way, existing code works as before.  If any driver registers two GPIO
devices, the first one will get a base of 0, and the second one will get
some other base.

quoted

quoted

gpiochip_find_base: found new base at 437

(...)

quoted

gpiochip_find_base: found new base at 362

These are awesome bases, just beautiful. Use this.

If you don't like seeing GPIO base numbers like this: use things
like the chardev and the tools in tools/gpio or libgpiod when
developing, and you will never see them. They should not make
a difference anyway.

Can you tell me more about the chardev?  I've always been using "echo X >
/sys/class/gpio/export", so I guess that's not the right way to do things.

Hi Timur,

take a look at the in-project documentation[1] and read the article[2]
about libgpiod. That should get you started.

Let me know if anything's not clear.

Thanks,
Bartosz

[1] https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/
[2] https://www.cnx-software.com/2017/11/03/learn-more-about-linuxs-new-gpio-user-space-subsystem-libgpiod/