Re: GPIO static allocation warning with v6.2-rcX

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Mon, Jan 23, 2023 at 3:55 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
>
> On Fri, Jan 20, 2023 at 11:46 AM Marco Felsch <m.felsch@xxxxxxxxxxxxxx> wrote:
> >
> > Hi all,
> >
> > I stumbled over the following warning while testing the new v6.2-rc4 on
> > a imx8mm-evk:
> >
> > [    1.507131] gpio gpiochip0: Static allocation of GPIO base is deprecated, use dynamic allocation.
> > [    1.517786] gpio gpiochip1: Static allocation of GPIO base is deprecated, use dynamic allocation.
> > [    1.528273] gpio gpiochip2: Static allocation of GPIO base is deprecated, use dynamic allocation.
> > [    1.538739] gpio gpiochip3: Static allocation of GPIO base is deprecated, use dynamic allocation.
> > [    1.549195] gpio gpiochip4: Static allocation of GPIO base is deprecated, use dynamic allocation.
> >
> > The warning was introduced by commit [1] but at least the following
> > drivers are parsing the alias for a gpiochip to use it as base:
> >  - drivers/gpio/gpio-mxs.c
> >  - drivers/gpio/gpio-mxc.c
> >  - drivers/gpio/gpio-clps711x.c
> >  - drivers/gpio/gpio-mvebu.c
> >  - drivers/gpio/gpio-rockchip.c
> >  - drivers/gpio/gpio-vf610.c
> >  - drivers/gpio/gpio-zynq.c
> >
> > According commit [2] it seems valid and correct to me to use the alias
> > and the user-space may rely on this.
> >
> > Now my question is how we can get rid of the warning without breaking
> > the user-space?
> >
> > [1] 502df79b86056 gpiolib: Warn on drivers still using static gpiobase allocation
> > [2] 7e6086d9e54a1 gpio/mxc: specify gpio base for device tree probe
> >
>
> The warning is there to remind you that static GPIO base numbers have
> been long deprecated and only user-space programs using sysfs will
> break if you remove it, everyone else - including user-space programs
> using libgpiod or scripts using gpio-tools that are part of the
> project - will be fine.
>
> Any chance you can port your user-space programs to libgpiod?
>
> The warning doesn't break compatibility so I'm not eager to remove it.
>

Oh and the drivers could use some updating. I'll take a look at them
one-by-one to see if there's anything other than sysfs that could
potentially break if we switch them to using dynamic allocation.

Bart