On Tue, May 19, 2015 at 04:12:35PM +0200, Linus Walleij wrote:
> On Mon, May 18, 2015 at 5:17 PM, grygorii.stras...@linaro.org
> <grygorii.stras...@linaro.org> wrote:
> > On 05/18/2015 06:08 PM, Johan Hovold wrote:
>
> >> GPIOs 160-191, platform/4805d000.gpio, gpio:
> >> gpio-171 (<irq-only> ) in hi IRQ-209
> >
> > In general agree, but i propose to do it as
> > GPIOs 160-191, platform/4805d000.gpio, gpio:
> > gpio-171 ((null) ) in hi IRQ-209 <irq-only>
> >
> > My intention is - this interface could be considered as more or less
> > stable, so
> > it is better to add additional information at the end of each line to avoid
> > potential breakage of User space SW (test/debug scripts).
>
> What? If I wanted a stable interface I would use sysfs and document
> the ABI in Documentation/ABI/*.
>
> debugfs is not ABI.
As I mentioned in my response to Grygorii, not everyone -- and most
notably apparently not even Linus Torvalds -- agrees on this:
"The fact that something is documented (whether correctly or
not) has absolutely _zero_ impact on anything at all. What makes
something an ABI is that it's useful and available. The only way
something isn't an ABI is by _explicitly_ making sure that it's
not available even by mistake in a stable form for binary use.
Example: kernel internal data structures and function calls. We
make sure that you simply _cannot_ make a binary that works
across kernel versions. That is the only way for an ABI to not
form."
https://lwn.net/Articles/309298/
In this case, it could be worked around by providing another debugfs
file with gpios used as IRQs, I guess.
Johan
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