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From: Alexander Dahl <ada@thorsis.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Kent Gibson <warthog618@gmail.com>
Cc: "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: Re: setting gpio-line-names in dts for sama5d2 SoC
Date: Thu, 18 Mar 2021 14:56:37 +0100 (CET)	[thread overview]
Message-ID: <1236506597.11463.1616075798037@seven.thorsis.com> (raw)
In-Reply-To: <CAHp75Vftrq66SweYKYprWBoi9X8csxe9ROaMorRFUjGSD8gNSQ@mail.gmail.com>

Hello Andy,

> Andy Shevchenko <andy.shevchenko@gmail.com> 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

  reply	other threads:[~2021-03-18 13:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-16 13:07 setting gpio-line-names in dts for sama5d2 SoC Alexander Dahl
     [not found] ` <CAHp75Vf05NN0dXUrMSOXBRuYRnQRHO_92itZ3ndOyX1oERWt=g@mail.gmail.com>
2021-03-17 12:33   ` Andy Shevchenko
2021-03-18  9:50     ` Alexander Dahl
2021-03-18 12:40       ` Andy Shevchenko
2021-03-18 13:56         ` Alexander Dahl [this message]
2021-03-18 14:59           ` Andy Shevchenko
2021-03-20 11:20             ` Linus Walleij

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