Re: setting gpio-line-names in dts for sama5d2 SoC

[Alexander Dahl <ada@xxxxxxxxxxx>]

Hello Andy,

> Andy Shevchenko <andy.shevchenko@xxxxxxxxx> hat am 18.03.2021 13:40 geschrieben:
> You may look into the commit
> 7cba1a4d5e16 ("gpiolib: generalize devprop_gpiochip_set_names() for
> device properties")
> which unifies the logic, but at the same time removed one comment:
> 
> -       /* If the chip defines names itself, these take precedence */

Well, that could be added again. And if that precedence stays as is, it should be documented in the gpio devicetree bindings to not cause further confusion?

> So, logic was that for a long time. And unfortunately I don't see how
> we may change this without breakage. This backs us to the discussion
> if the name of the line is ABI or not.

I want to point out one point for consideration. There's usually a difference between the SoC and the boards using that SoC. So those pins are all the same from the chips point of view and the default names are set in a driver related to the chip (family).  However the line names set in device tree are probably related to a board.  Obviously different boards may have different line names, even when using the same SoC.

In other words: if I design a new board, there's no interface I would break, at least not from the userspace point of view just looking at the line names, or is there?

Thanks for looking into this.

Greets
Alex